Abstracts of FUSE Cycle 2 Guest Investigator Programs The following abstracts are presented as submitted to NASA in response to NRA-00-OSS-05 in July 2000. In the peer review process some proposals may have been reduced in scope or targets. Such changes are not reflected in these abstracts. ------------------------------------------------------------------------------ Prog ID: B001 PI: Bianchi, Luciana Institution: The Johns Hopkins University Title: Central Stars of Planetary Nebulae in the Large Magellanic Cloud We propose to observe with FUSE a sample of Planetary Nebulae in the Large Magellanic Cloud for which we have analysed HST UV and optical spectra. The flux is dominated by nebular continuum in the HST range. Instead, the far-UV spectrum will provide a direct measurement of the stellar continuum, enabling a better measurement of stellar temperature and absolute luminosity, useful to refine post-AGB evolution and nebular ionization modeling. The FUSE spectra will also reveal the hottest layers of the stellar wind, yielding an accurate measurement of the terminal velocity and mass loss rate, which is important to model the nebular dynamics, and to understand the central stars properties and evolution. The H_2 transitions in the FUSE range provide a powerful way to measure the circumstellar molecular gas, which - added to the mass of the central star, and of the ionized shell previously determined, will allow us to test theoretical initial-final mass relations. The far-UV data will be a unique and valuable contribution to constrain the stellar and nebular properties of these objects, which are effectively at a single, unambiguous distance. ------------------------------------------------------------------------------ Prog ID: B003 PI: Welsh, Barry Y. Institution: UC Berkeley Title: Probing the Local Bubble-halo connection through the Local Interstellar Chimney We shall probe the ionization state and kinematics of the lower halo-Local Bubble interaction region using hot white dwarf stars of known, increasing distance away from the galactic plane up to z sim 0.3 kpc that of neutral gas. Our main goal is to obtain better constraints on the location of the hot gas of the Local Bubble and the associated conductive interfaces. We shall also search for signs of the infall or outflow of neutral andor ionized gas in this particular region (which could be related to a galactic fountain), and investigate the way the kinetic temperature, electron density, element abundancesdepletions and gross velocity structure of gas in the Local Bubble varies as a function of increasing height above the galactic disk as it merges into the lower galactic halo. ------------------------------------------------------------------------------ Prog ID: B004 PI: Heckman, Timothy Institution: Johns Hopkins University Title: The Far-UV Spectra of Powerful Starbursts Starbursts are a significant component of the present-day universe, and offer unique laboratories for both studying the processes that have regulated the formation and evolution of galaxies, and for testing models of high-mass stellar evolution. We propose to exploit the unique strengths of FUSE to obtain high-resolution (15 to 20 km s^-1) high quality SN sim 10) spectra of the four most powerful UV-bright starbursts in the local universe. These have bolometric luminosities comparable to the Lyman Break galaxies at z sim3. Together with the lower-power starbursts observed by FUSE in Cycle 1, the sample will span nearly the entire ranges of luminosity and metallicity seen in local starbursts. The spectra will be used to study 1) the coronal-phase gas that may dominate the energetics of starburst-driven superwinds 2) the H_2 that probably dominates the ISM mass and regulates the star-formation ) the starburst dust-attenuation law in the unexplored FUV window 4) the stellar content of the starburst (thereby probing the IMF and burst history). The relatively large FUSE apertures allow us to obtain high-resolution spectra of nearly the entire starburst (rather than small pieces, as with HST and STIS). ------------------------------------------------------------------------------ Prog ID: B006 PI: Boroson, Bram Institution: NASA Goddard Space Flight Center Title: Far-UV Spectroscopy of Scorpius X-1 We propose to investigate the mass transfer in the important Z source X-ray binaries by resolving the far-UV emission lines in Scorpius X-1 to reveal Doppler-shifted velocities. The far UV region contains strong emission lines that are sensitive to X-ray illumination and provide valuable diagnostics of physical conditions in the accretion disk. We will use the strengths of ionO6, ionC3, and ionN3 lines as density, temperature, optical depth, and abundance diagnostics. Covering an entire 0.787 day binary orbit will allow us to look for orbital Doppler shifts and to apply the method of Doppler tomography. We will search for variability on time scales of seconds, resulting, for example, from reprocessing of an X-ray flare by the accretion disk. ------------------------------------------------------------------------------ Prog ID: B008 PI: Boroson, Bram Institution: NASA Goddard Space Flight Center Title: Far-UV Spectroscopy of Hercules X-1 HerculesX-1 is the prototypical X-ray binary pulsar, and is fortuitously located behind a very low column density of absorbing gas. We propose to observe the far UV spectrum continuously for a complete binary orbit. From our previous HSTSTIS observations, we expect to be able to separate broad and narrow emission line components, probably due to the accretion disk and X-ray heated atmosphere of the normal star. Concentrating on the O 6 doublet will allow us to probe higher degrees of X-ray ionization than the lines seen with STIS, and with the larger wavelength separation of the doublets, there will be less of the confusing overlap presentin the STIS spectra. From the data, we will form Doppler tomograms, search for evidence of a stellar wind driven from the companion or the accretion disk by X-ray heating, and look for reprocessed pulsations or UV quasiperiodic oscillations. We can measure temperatures using the C,IIIlambda977,1176 lines and densities using the ionN3lambda990 Bowen line. ------------------------------------------------------------------------------ Prog ID: B010 PI: Chu, You-Hua Institution: University of Illinois Title: Mapping Hot Gas in a Pristine H, sc ii Region The H,sc ii region N11B in the Large Magellanic Cloud (LMC) contains an OB association that is dominated by main-sequence members and contains several O3 stars, the most massive of stars. The velocity dispersion of the 10^4 K ionized gas in N11B is among the smallest in LMC H,sc ii regions. The stellar content and gas kinematics suggest that N11B is a pristine H,sc ii region in which no supernova explosion has occurred. Thus, N11B provides an ideal site to study the interaction between fast stellar winds and the interstellar medium (ISM). medskip We request FUSE observations of nine stars in N11B. These nine stars span a large spatial coverage along the E-W direction and a wide range of spectral types from O3 to B1. Only one of the stars, an O5.5V, is surrounded by a visible ring nebula, indicating the existence of a wind-blown bubble. The FUSE observations of the O,sc vi lines will allow us to map the distribution of hot gas in N11B and to study how fast stellar winds interact with the ambient ISM. We also request an observation of a comparison target in a neighboring superbubble to diagnose possible spillover of its hot gas and large-scale foreground ISM structures at the same velocity. ------------------------------------------------------------------------------ Prog ID: B013 PI: St-Louis, Nicole Institution: Universite de Montreal Title: A Systematic Study of Colliding Winds in Wolf-Rayet (WR) Binaries. I. Carbon-Rich WR stars. We propose to secure a time sequence of ultraviolet (UV) spectra for a series of WR+O binary systems to study the physical parameters and the structure of the bow shock zone formed when the winds of the two hot stars collide. Of particular importance in the sl FUSE UV range is the presence of a broad spread of emission lines with different ionization levels, ranging from Othinspace VI to Cthinspace III. These lines are expected to arise in the bow shock zone at progressively larger distances from the X-ray heated bow head, as the compressed plasma flows outward along the shock cone and cools. The study of how these lines vary with orbital phase in a selection of WCWO binaries will allow us to map out the structure and kinematics of the bow shock for a broad variety of systems. This in turn will provide useful constraints on the basic parameters of the winds as well as the collision process itself. The 5 systems proposed are known from optical data to show strong wind-wind collision effects. ------------------------------------------------------------------------------ Prog ID: B015 PI: Crampton, David Institution: HIA, NRC of Canada Title: Supersoft X-ray binaries This is a continuation of a program assigned time in cycle 1. We propose to obtain phase-resolved FUSE spectra of two supersoft X-ray binaries, achieving SN >10 over 1 - 2AA in orbital phase bins of leq0.1P. The emission line features in the FUSE wavelength range cover a wide range of ionization giving a unique dataset for determination of the binary parameters, component masses, and disk structures which cannot be provided by optical and HST data. The O VI lines may provide unique measures that define the stellar masses. We will also use the combined data for each system to detect and measure high-velocity lines from bi-polar jets which are seen in the optical spectra of one system. High-ionization lines from these jets are of particular interest since they are formed in the innermost region where the jets are undergoing their collimation and acceleration. An improved understanding of jets has wide astrophysical implications. ------------------------------------------------------------------------------ Prog ID: B016 PI: Hutchings, John B. Institution: HIA, NRC of Canada Title: Far ultraviolet spectra of classical X-ray binaries We propose to obtain binary-phase-resolved FUSE spectra of three classical X-ray binaries (Sco X-1, X1822-37, and LMC X-3) through their orbital cycles. Each of these systems is the prototype of its type of system, and each has unsolved problems associated with it. The optical and ultraviolet spectra of the first two are dominated by an accretion disk. The third, LMC X-3, contains a luminous B supergiant, whose light is dominant in the visible, but opticalUV data also reveal the presence of a large accretion disk. FUSE data will allow study of these disks over a wide range of temperature and density, hence revealing physical properties of these accretion disks and kinematics of the gas. ------------------------------------------------------------------------------ Prog ID: B018 PI: Lequeux, James Institution: Observatoire de Paris Title: Molecular and atomic hydrogen, abundances and stellar content in giant extragalactic HII regions FUSE offers the unique possibility for obtaining far-UV spectra in the direction of giant HII regions in nearby galaxies. The ionizing star cluster is a far-UV source, and the interstellar matter in front will produce absorption lines of H, H_2 and various atoms and ions. We will obtain the H_2H ratio, the HDH_2 ratio, the COH_2 ratio, the dustgas ratio as well as the abundances of various ions, and an integrated spectrum of the ionizing cluster which will be compared to our evolutionary models. We have already tested this technique by observing with FUSE the ionizing cluster of the blue compact galaxy I Zw 18. We wish to observe 8 targets having radial velocities differing by more than 130 km s^-1 from those of the Galactic interstellar gas. For these targets, the lines will be well separated from the galactic absorption lines. ------------------------------------------------------------------------------ Prog ID: B022 PI: Thuan, Trinh Xuan Institution: University of Virginia Title: The Interstellar Medium of Blue compact dwarf galaxies Blue compact dwarf (BCD) galaxies are metal-deficient and thus constitute excellent nearby laboratories for studying how the properties of the interstellar medium (ISM) in galaxies change with metallicity. Our sample consists of 4 BCDs chosen to span the metallicity range from 15 to 12 of the solar metallicity. This sample will extend the metallicity range covered by our Cycle 1 observations (141 to 110 solar). The proposed FUSE observations will allow us to investigate the 1) H_2 content of BCDs as a function of metallicity. No H_2 line has been detected in the 2 very metal-deficient BCDs which have been observed by FUSE so far. Will diffuse H_2 be present in more metal-rich BCDs and with less UV radiation density? 2) the structure of the ISM in BCDs. Analysis of 2 BCDs observed by FUSE in Cycle 1 (IZw18 and Mrk 59) show that in the first, the ISM appears to be relatively homogeneous while in the second, it is very clumpy. What are the factors which determine the gas clumpiness in BCDs 3) the abundances in the ISM. Analysis of the FUSE spectrum of Mrk 59 showed C, N, O, Si, Fe and S absorption lines which allow to derive abundances in the ISM using photoinization models. How do these abundances compare with the abundances derived from the emission-line optical spectra? 4) the evolutionary history and stellar winds in BCDs by detecting the P Cygni profiles of high ionization S VI and O VI lines. ------------------------------------------------------------------------------ Prog ID: B023 PI: Perinotto, Mario Institution: Universita di Firenze Title: FUSE Observations of WC-PG1159 Central Stars of Planetary Nebulae We propose to observe three central stars of planetary nebulae to study their winds, and perform a detailed atmospheric comparison. Groundbased and IUE observations show these stars, A30, A78, and Lo-4, to be nearly identical in temperature, radius, and masss, although IUE spectra show very different wind characteristics. The limitations of the previous UV observations, the lack of O IV and/or lack of O V 1371AA P Cyg, will be addressed with the FUSE observations. We will perform detailed analysis of the photospheres and winds of these stars using the latest version of PHOENIX. Finally, we will also include analyses of four similar stars for which IUE spectra are available but that are already FUSE targets PI targets NGC 1535, NGC 7094, and IC 3568, and the Cycle 1 GO target NGC 6210. ------------------------------------------------------------------------------ Prog ID: B025 PI: Marggraf, Ole Institution: Universitat Bonn Title: Fine structure in interstellar H_2 clouds seen against an open star cluster The physical conditions in extended molecular clouds are still not well known. Most of our knowledge is based on CO emission, widely used to map the structure of molecular gas. Since there is no H_2 emission available from the cold cores of molecular clouds, the H_2 abundance is usually calculated by linking it to that of CO. Direct observation of H_2, the most abundant molecule in the universe, could provide information on the physical state in the core of a molecular cloud and on the spatial variation of this physical state over small scales. We plan to observe a sample of seven sightlines towards the Galactic open cluster NGC6231. The small angular separation of the target stars of overall 5.8arcmin will be used to examine the structure of the molecular interstellar medium down to scales of less than 0.3pc. Physical parameters like abundances of H_2 and various metals, depletions, temperatures, electron densities, and the level of radiation will be determined and their spatial variation will be examined. ------------------------------------------------------------------------------ Prog ID: B027 PI: Vladilo, Giovanni Institution: Osservatorio Astronomico di Trieste Title: H_2 versus dust in the Magellanic Clouds a paradigm for studies of Damped Ly Alpha systems The most abundant interstellar molecule, H_2, is associated with the presence of dust which acts as a catalyst for molecule formation. The abundance ratio of a refractory to a non-refractory element, such as the CrZn ratio, is a good diagnostic tool of interstellar dust content. In Galactic interstellar clouds, high molecular fractions, f(H_2)equiv ,N(H_ 2 )N(HI)+2,N(H_ 2 ), are only found along sightlines of high Cr depletion, even though f(H_2) and CrZn do not show a linear correlation. On the contrary a linear correlation between f( H_2) and CrZn has been discovered in high-redshift molecular clouds from the study of damped Lyalpha systems (DLAs) showing H_2 absorption Levshakov et al. 2000). In order to contrast the properties of local galaxies with those of the high redshift galaxies associated with DLAs it is important to compare environments of similar metallicity. The Magellanic Clouds (MCs), with their low metallicity, are ideally suited for this purpose. FUSE and ORFEUS have already allowed the measurement of H_2 along several MCs sightlines. Unfortunately, the CrZn ratio has been determined only for three MCs sightlines Roth & Blades, 1997), for none of which H_: 2 has been searched for. We propose to use FUSE to measure H_2 along these three sightlines in order to compare molecular fraction versus dust content in the MCs, in the Milky Way and in DLAs. In this way we expect to obtain fresh clues on the nature of DLA galaxies and on the interstellar medium of the MCs. ------------------------------------------------------------------------------ Prog ID: B029 PI: Meyer, David M. Institution: Northwestern University Title: Small-Scale Interstellar Structure Toward the Open Cluster chi Persei We propose to obtain FUSE observations of the interstellar H_2 and CI absorption toward six early-type stars in the core of the open star cluster chi Persei. High-resolution optical observations of the interstellar Na I absorption toward these stars and others in the core of chi Per have revealed a rich variety of small-scale diffuse ISM structure in both the distant Perseus and more local Orion spiral arms. At the approx. 1arcmin scales typically probed by these stars, this structure corresponds to respective physical length scales of 0.6 and 0.15 pc in the Perseus and Orion arm gas. By comparing the abundances and excitation of H_2 and CI in these six closely-spaced chiPer sightlines, we plan to (1)investigate the possibility that the high-velocity NaI structure is associated with a density-wave shock interaction with gas on the inner edge of the Perseus arm, and (2)study the physical character of the small-scale Orion arm structure that seems to be evident not only in the NaI lines but also the lambda5797 diffuse interstellar band. ------------------------------------------------------------------------------ Prog ID: B030 PI: Federman, Steven R. Institution: Univ. of Toledo Title: Effects of Star Formation and Stellar Death on Interstellar Gas Associated with Cep OB2 Interstellar clouds that give birth to stars are subsequently affected by those stars. In particular, massive stars, through their stellar winds, intense ultraviolet radiation, and their terminal supernovae explosions, contribute to the dispersal of the clouds and seed the clouds with newly synthesized elements. In order to understand the details of cloud dispersal, on the one hand, and chemical evolution, on the other, in a site of star formation, the interstellar material toward stars in Cep OB2 will be probed through a study of absorption lines. After three episodes of star formation, the material in front of Cep OB2 is all that remains of the original molecular cloud. Analysis of H_2 absorption will yield information on the physical conditions for the material; gas temperature and incident ultraviolet flux will be extracted from the measurements. These derived quantities will help constrain models of the evolution of interstellar clouds on Galactic scales. A search for the F small I resonance line at 954 AA will establish the interstellar F abundance, which may be used to resolve the origin of this element is F synthesized primarily in Type II supernovae, whose effects should be revealed in a region of ongoing massive star formation, or in asymptotic giant branch stars ------------------------------------------------------------------------------ Prog ID: B032 PI: Gruendl, Robert Institution: University of Illinois Title: Hot Gas in Planetary Nebulae Planetary nebulae (PNe) are formed by the interaction between the fast stellar wind and a previous slow wind. In this interacting stellar wind model, the fast stellar wind which fills the PN interior is shocked and heated to X-ray-emitting temperatures. On the other hand, ROSAT observations of 80 PNe show indications of emission from a 10^6K plasma in only 6 PNe. Chandra has observed 3 of these PNe and 2 of them, BD+30^circ3639 and NGC,6543, have finally been resolved and show that hot gas fills their central cavities. Thus, to date the presence of 10^6K hot gas has only been unambiguously detected in two PNe. smallskip The deficit of detections of X-ray emission from PNe suggests that the PN interiors may have a lower temperature. Heat conduction processes, and the mixing and evaporation of the cold dense nebular material into the hot interior will enhance the cooling rate and might account for the temperature drop of the PN interiors. The determination of the physical structure and state of the hot gas in the PN interiors is necessary to address the details of the interaction of the winds (including the interface physics) in order to understand the physical structure and evolution of PNe. smallskip We propose to observe the nebular absorption of OVI against the spectrum of the PN central star to probe the physical conditions of PN interiors. Whereas the nebular absorption lines of CIV and NV can be produced by photoionization from the hot central star of PNe, the OVI lines offer a reliable diagnostic of the presence of sim3times10^5K gas for central stars as hot as 125,000K. These lines can only be observed by FUSE. ------------------------------------------------------------------------------ Prog ID: B033 PI: Fontaine, Gilles Institution: Universite de Montreal Title: A test of Pulsation Theory in Hot B Subdwarfs There are currently of the order of 15 hot B subdwarf (sdB) stars which are known to exhibit low-amplitude (a few to tens of millimag), short-period (100-500 s), multiperiodic luminosity variations. These pulsations are thought to be driven by an opacity bump linked to the presence of a local enhancement of the iron abundance in the envelopes of sdB stars. Such an enhancement results quite naturally from the diffusive equilibrium between gravitational settling and radiative support in the stellar envelope. Nevertheless, surveys for pulsating sdB stars show that, in several instances, variable and non-variable objects with similar effective temperatures and gravities may coexist in the HR diagram. This result suggests that an additional parameter, perhaps a weak stellar wind, might affect the extent of the iron reservoir and thus the ability of the latter to drive pulsations in sdB stars. Fortunately, it is expected that such a wind might also leave its mark on the photospheric heavy element abundance patterns. The intended FUSE observations will i) permit a direct comparison of the heavy element abundance patterns in variable and nonvariable stars of similar atmospheric parameters; ii) provide a consistency check with our wind models; and iii) provide a test of the currently-favored explanation for the driving of the observed pulsations. ------------------------------------------------------------------------------ Prog ID: B034 PI: Mouchet, Martine Institution: Observatoire de Paris, Section de Meudon Title: The origin of peculiar UV line ratios in the Magnetic Cataclysmic Variable AE Aqr We propose to observe the atypical Magnetic Cataclysmic Variable (MCV) AE,Aqr which is one of the few systems showing anomalous UV emission line ratios. The far-UV spectra will provide a crucial test on whether this system is characterized by peculiar ionization conditions or by anomalous non-solar abundances. The measurements of the resonance OVI emission line, combined with those of the NIII and CIII lines, will provide strong clues to discriminate between these different possibilities. Other hallmarks of AE,Aqr are its extreme strong flaring activity, and a unique spectrum extending from TeV to radio wavelengths likely due to the propeller mechanism related to the fast magnetized white dwarf spin (33 sec). A total on-source exposure time of 40 ksec, will allow us to study the phase-resolved far-UV spectrum along the rotational and orbital (9.98 hr) periods in order to constrain the temperature and structure of the accretion-heated polar regions of the white dwarf. We will also observe for the first time far-UV flares which will provide further parametrization of the active regions thought to be produced by blob impacts at the magnetosphere. ------------------------------------------------------------------------------ Prog ID: B038 PI: Catala, Claude Institution: Observatoire Midi-Pyrenees Title: High temperatures and disks around PMS stars FUSE Spectra of Three Herbig AeBe Stars Previous optical and UV (IUE & HST) observations have shown that the intermediate mass PMS Herbig AeBe stars possess strong stellar winds and dense chromospheres. These winds and chromospheres are the seat of active variable phenomena, most likely linked to surface magnetic fields. Detailed models of the outer atmospheres of these stars have been constructed, and predict that the Lybeta line at 1025 AA and the C III resonance line at 977 AA must appear with an intense emission component. We intend to check this prediction with FUSE observations, and take advantage of the observed fluxes and profiles to further constrain the models of these stars. In addition, we will also search for the presence of H_2 absorption bands between 950 and 1150 AA, which are expected if these stars are surrounded by massive accretion disks. ------------------------------------------------------------------------------ Prog ID: B039 PI: Kwok, Sun Institution: University of Calgary Title: Carbon, Nitrogen, and Helium Abundances in Planetary Nebulae We propose to use FUSE to obtain high resolution spectra of 5 planetary nebulae. The FUSE spectral range contains lines from 3 different ionization stages of carbon, allowing for a much better determination of the ionization correction factors necessary for accurate abundance determination. The carbon abundance in planetary nebulae is crucial in the testing of nucleosynthesis models and dredge-up theories on the AGB. FUSE provides a unique opportunity to test these models. We have chosen both type I and type II planetary nebulae for this study, as the latter group in particular are expected to have unusual abundances of the CNO elements. The FUSE observations will also provide some data on the N and He abundances for these higher excitation nebulae. ------------------------------------------------------------------------------ Prog ID: B043 PI: Wood, Janet Institution: San Diego State University Title: Probing Shocks and Winds in the Peculiar Binary Star VSagittae VSge is an extremely unusual close binary. Once thought to be related to CVs or LMXBs, it is now suggested to be a colliding wind system. If so, with its 12.3 hr period, it is the shortest orbital period colliding wind system known. It appears to be undergoing a short-lived phase of evolution, and may be in the very final stages of common envelope evolution. VSge shows high and low photometric states, possibly related to its evolutionary state, in which the spectroscopic behaviour changes dramatically. High resolution, phase-resolved UV spectra have been studied previously in the low state but no such observations exist for the high state and there are no published observations in the FUSE FUV wavelength range. Still-unexplained phenomena occur in VSge which need to be investigated before the colliding wind model can be firmly established, including the mechanism causing the high and low states. We speculate that this mechanism is related to a change in wind behaviour but this idea needs to be tested by observing and modeling the wind line profiles around the binary orbit in both states. We therefore propose to obtain orbital phase-resolved FUSE spectra of VSge in two epochs. With its rich spectrum of wind emission lines at a variety of abundances and ionization states, FUSE will allow us to model the structure and kinematics of the stellar winds and the shock front in the binary and probe a new regime of stellar wind collisions in evolved close binary systems. ------------------------------------------------------------------------------ Prog ID: B045 PI: Kirshner, Robert P. Institution: Harvard University Title: Far-Ultraviolet Spectra of a Supernova to be Named Later We propose using FUSE to observe a newly-discovered supernova during Cycle2 as a target of opportunity. Our experience with HST and IUE ultraviolet spectra shows how informative they can be. With FUSE, we can explore a previously unobserved part of the spectrum where many important lines will help in building a complete picture, especially of circumstellar interactions. The resolution of FUSE is excellent for this purpose because it neatly separates circumstellar features from interstellar lines and the ability to move promptly to a good target is a very large advantage over HST. A recent example of a typeII, SN 1998S, illustrates what a STIS spectrum can (and cannot) do, and gives us a solid basis for predicting what is required for measurements with FUSE. We hope to continue our HST Target-of-Opportunity program, and we would aim to combine our FUSE observations both with our ground-based data and with STIS data. The probability of having one suitable target per year is high, but not unity. In Cycle 1, we exercised restraint because there was not a suitable target for FUSE. We hope for better luck in Cycle 2. ------------------------------------------------------------------------------ Prog ID: B046 PI: Lauroesch, James Institution: Northwestern University Title: The Physical Character of Small-Scale Interstellar Structures Recent optical and radio studies have found convincing evidence for pervasive small-scale structure in the diffuse ISM on 10-10^4 AU scales. The seemingly ubiquitous existence of such small, dense pockets of gas in the diffuse ISM is an important puzzle since the inferred over-pressures of these clumps imply lifetimes of only a few thousand years before they should diffuse away. Measurements and comparisons of the interstellar absorption line profiles towards members of resolvable binary star systems with FUSE can greatly expand our knowledge of the physical conditions and abundances in these clumps. Therefore, we propose to obtain FUSE observations of the interstellar H_2 absorption lines towards six members of three multiple star systems of varying separations with the goal of deriving accurate densities, temperatures, and radiation fields for the clouds associated with the observed small-scale structures in these sightlines. By using the many lines of H_2, we can determine if these clumps are indeed as dense as they appear and discriminate between competing models for the origin of these features. ------------------------------------------------------------------------------ Prog ID: B047 PI: Szkody, Paula Institution: University of Washington Title: Accretion Onto Magnetic White Dwarfs We will observe the far UV emission of the highest field (230 MG) magnetic cataclysmic variable AR UMa and of the typical field (30 MG) polar VV Pup in order to confront theories of buried shocks and accretion heating. A measurement of the far-UV flux in AR UMa will help to resolve ambiguities in our HST data about the field strength and the heating of the white dwarf under extreme field conditions. In VV Pup, the ability to directly view the white dwarf, combined with a simple geometry where the primary pole rotates behind the white dwarf for part of its short orbital period, allows a clear separation of the contributions of the unheatedheated white dwarf and the accretion funnel. The high resolution and large excitation range of lines covered by FUSE allows the delineation of the composition, temperature, density and velocity of the line-forming regions in the accretion funnel and at the photosphere of the white dwarf. The analysis of FUSE data on the 2 very different systems AR UMa and VV Pup will provide a clearer understanding of the conditions of magnetic accretion and their ultimate effect on the underlying white dwarf. ------------------------------------------------------------------------------ Prog ID: B048 PI: Szkody, Paula Institution: University of Washington Title: Understanding the Enigmatic SW Sex Stars The SW Sex stars are a subgroup of cataclysmic variables that are known for several peculiar features, including high excitation single-peaked lines in their spectra, absorption features in the low excitation lines, phase offsets between the radial velocity curves and photometric eclipse times, unusual high velocity components, and orbital periods between 3-4 hrs. The cause of these peculiarities is controversial, with possibilities ranging from mass transfer stream impact and overflow at high mass transfer rates to magnetic propellers, winds and jets. As many of these suggestions depend on the inclination of the system, we propose to confront such theories by contrasting FUSE observations of the low inclination SW Sex star LS Peg and a more typical high inclination system DW UMa. The high quality, high resolution FUSE spectra we will obtain will allow us to construct detailed models of the inner accretion disk and velocity flows of both systems. This will resolve which of the properties are geometry dependent, and thereby lead to a basic advance in our understanding of this class of objects and ultimately, of the general effects of high mass transfer in close binaries. ------------------------------------------------------------------------------ Prog ID: B051 PI: Vennes, Stephane Institution: Australian National University Title: Surface Abundance Pattern of Accreting White Dwarfs in Non-Interacting Close Binaries Our HST GHRS investigation of white dwarfs in the EUV-selected close binaries EUVE J0720--317 (WD0718-316), EUVE J1016--053 (WD1013-050), and EUVE J2013+400 (WD2013+400) revealed photospheric abundances of helium and carbon much larger than measured in isolated white dwarfs with similar parameters. This peculiar abundance pattern bears the signature of diffusive equilibrium supplied by accretion from a close red dwarf companion. Additional evidence for the accretion scenario emerged with the discovery of V471 Tau-like EUV variability in EUVE J0720--317 and J1016--053, which suggests abundance inhomogeneities across the stellar surface. We propose to obtain high quality FUSE spectra of these three binaries and secure abundance measurements of He, C, Si, P, and S. The data will enable a study of the distinctive roles played by accretion and selective radiation pressure. Because selective radiation pressure on He and Si is inefficient, their abundance is determined by steady-state equilibrium between the accretion flow and downward diffusion and holds a ratio of log(SiHe)-3.7, while the abundance of C, P, and S should be determined by radiation pressure correlated with effective temperature. We also propose to study the surface abundance pattern of the white dwarf in EUVE J0720--317 with a series of spectra resolving the rotation phase. The data will also improve orbital parameters initially established in GHRS measurements. ------------------------------------------------------------------------------ Prog ID: B052 PI: Barstow, Martin Institution: University of Leicester Title: THE EVOLUTIONARY LINK BETWEEN CSPN AND DA WHITE DWARFS We propose FUSE observations of a sample of central stars of old planetary nebulae to study the evolutionary link between them and the H-rich DADAO white dwarfs. Analysis of the H Lyman and OVI resonance lines provides a unique determination of T_eff and log g for each star, taking into account the heavy element abundances, which are known to affect the temperature determination. We will measure detailed element abundances from the metal line strengths in the high resolution FUSE spectra. Importantly, FUSE gives us access to absorption lines of several species which cannot be studied in any other wavelength range. From this work, combined with observations of a smaller number of related PI targets, when they appear in the public archive, we will re-establish the temperature scale for these stars and compare their compositions with their supposed white dwarf descendants. A search for ongoing mass-loss will be carried out, looking for P-Cygni signatures in the CIII and OVI resonance lines. Evidence of current activity might explain the discrepancies often observed between the PN kinematic ages and the stellar evolutionary timescale. ------------------------------------------------------------------------------ Prog ID: B053 PI: Barstow, Martin Institution: University of Leicester Title: TEMPERATURE, GRAVITY AND COMPOSITION OF DAO WHITE DWARFS We propose FUSE observations of a sample of DAO white dwarfs to study their relationship with the DAO central stars of planetary nebulae and the DA white dwarfs, where helium is not, or no longer, present. We will analyse the H Lyman lines, providing a unique determination of T_eff and log g for each star, taking into account the heavy element abundances, which are expected to significantly affect the temperature determination. These abundances will be determined from the heavy element lines detected in the high resolution FUSE spectra. This is particularly important for species which cannot be detected in any other wavelength range. With the improved accuracy of self-consistent determinations of elemental abundances and T_eff we will be able to compare the compositions with the CSPN and DA white dwarfs. With multiple exposures spread across several orbits, we will be able to use the strongest of the narrow metal lines detected to check for evidence of binarity. ------------------------------------------------------------------------------ Prog ID: B054 PI: Wesemael, Francois Institution: Universite de Montreal Title: Diffusion and Weak Stellar Winds in Hot B Subdwarfs The hot B subdwarf (sdB) stars are low-mass, core-helium burning objects located on the extreme horizontal branch; they are the progenitors of low-mass white dwarfs. Their effective temperatures range from 20,000 K to 50,000 K, and their hydrogen-rich atmospheres display significant abundance anomalies of helium and heavy elements for example, carbon is generally underabundant, and that deficiency appears to increase with increasing T_ eff; the nitrogen abundance remains nearly solar over the temperature range, while silicon appears moderately deficient below 30,000 K, but is strinkingly underabundant at higher temperature. Previous studies of these abundance patterns suggest that downward gravitationnal settling and upward radiative forces play important role in determining the observed abundances, but also that weak stellar winds, with associated mass loss rates of the order of 10^ -15 -10^ -13 ,M_, yr ^ -1 , might thread the atmospheres of sdB stars. We propose to secure FUSE spectra of a dozen of these stars, with the specific aims of extracting abundances for a dozen chemical species, mapping the variation of the abundance of each element as a function of effective temperature, confronting the observed abundances with the predictions of the weak wind model, and investigating the self-consistency of that model. The analysis of superficial abundances in sdB stars provides us with a unique tool for the determination of the properties of the stellar winds present in those objects, despite the fact that these winds are too weak to be detected directly. ------------------------------------------------------------------------------ Prog ID: B055 PI: Burleigh, Matthew Institution: University of Leicester Title: The fundamental parameters of white dwarfs in Sirius-type binary systems We will use FUSE to accurately determine the fundamental parameters (T_eff , log g, radius and mass) of a sample of white dwarfs in Sirius-type binary systems. Far-ultraviolet spectroscopy of the H Lyman series is the only means available to achieve this goal. We will then use the mass determinations to investigate the initial-to-final mass relation for white dwarf stars. In addition, Hipparcos provides us with well constrained parallaxes for many of the primaries in this sample. We will use this data, together with the parameters determined with FUSE, to retrieve the stellar masses and hence test the white dwarf mass-radius relation, in particular the high mass end. Finally, we will search for evidence of elements heavier than He in these stars photospheres and in the circumstellar environment, and determine their abundances. This proposal is complimentary to our Cycle 1 program (A054, PI Burleigh), in which we are observing 11 targets with T_eff >= 35,000K. We now seek time to observe those systems with cooler white dwarf secondaries, T_eff <= 35,000K. We note that some of these systems have been resolved in our complimentary HSTWFPC2 UV-imaging program, and within a few years we will be able to derive astrometric masses for the white dwarfs in several cases. ------------------------------------------------------------------------------ Prog ID: B056 PI: Bregman, Joel Institution: University of Michigan Title: The Truth About Cooling Flows in Elliptical Galaxies The most fundamental quantity needed to understand cooling flows in elliptical galaxies is the rate that gas cools from the hot million degree state to the warm ionized or neutral state. In AO1, we measured this rate to be about an order of magnitude lower than the cooling flow prediction in two elliptical galaxies. If generally true, this will lead to a major revision of the model, and here we propose observations to determine the cooling rates in a complete sample of nearby ellipticals. Together with X-ray and optical observations, the FUSE data will determine which alternative models are at work, such as those where much of the gas is flowing outward rather than inward. ------------------------------------------------------------------------------ Prog ID: B058 PI: Gonzalez-Riestra, Rosario Institution: INTA Title: Far UV Spectroscopy of the VV Cep System KQ Pup KQ Pup is one of the most representative examples of the VV Cep binary systems. It is an spectroscopic, non--eclipsing, binary with a period of 26.7 years. The UV spectrum is dominated by the continuum of the hot star (presumably B0V), with two types of lines superimposed on it narrow absorptions --with or without red emissions-- of singly ionized elements, and broad absorptions of resonance lines with a wide ionization range and of excited lines of doubly ionized metals. The orbit of the system is very eccentric, and therefore a strong enhancement of the interaction effects is expected associated to the periastron passage, which took place in May 1999. Conjunction (M supergiant in front of the B star) will occur during the period covered by the FUSE Cycle 2. In this geometrical configuration we will able to see the side of the B star facing the M supergiant, as well as a signature of a possible eclipse (not observed so far) by the extended M--star atmosphere or by its inner wind. The FUSE data will provide a deeper insight into the nature of the hot star and a better determination of the complex geometry of the line forming regions. ------------------------------------------------------------------------------ Prog ID: B060 PI: Fitzpatrick, Edward L. Institution: Villanova University Title: A Study of the Atmospheres of the Main Sequence B Stars We request observing time with FUSE to obtain far-UV spectra of 5 mid- to late B-type main sequence stars (BVs) in the Orion OB1 association. These data will be part of a comprehensive investigation of the ability of current model atmosphere calculations to reproduce the observed properties of the BVs, including the overall energy distributions and the detailed absorption line spectra. This study will provide a benchmark and a reality check for studies of more exotic early-type objects, since the BVs are the hottest and most luminous stars whose atmospheres can be modeled with simple assumptions, such as LTE, plane-parallel geometry, and hydrostatic equilibrium. The targets span a T_eff range of 11000--17000 K, a vsini range of nearly 400 km s^-1, are lightly reddened to minimize the impact of the ISM, and are located in a relatively small volume of space to minimize differential extinction effects. The sample is large enough to allow general conclusions to be drawn and to distinguish individual peculiarities from general trends. This program will produce a valuable archive of uniformly high quality far-UV spectra uncompromised by interstellar absorption and spanning a stellar temperature range within which the 900-1200 AA flux constitutes a significant fraction of the total emitted stellar energy and is extraordinarily sensitive to stellar atmosphere conditions. These data will be ideal for evaluating the success of current stellar atmosphere calculations and examining the effect of rapid rotation on the far-UV energy distributions of the BV stars. ------------------------------------------------------------------------------ Prog ID: B062 PI: Mathur, Smita Institution: The Ohio State University Title: FUV Spectroscopy of Narrow Line Seyfert 1 Galaxies We propose FUSE observations of two bright well-studied narrow-line Seyfert 1 galaxies (NLS1s), Akn 564 and NGC 4051, to determine the properties of the emission lines, absorption lines, and the continuum in the FUV region of this important class of AGNs. The FUV bridges an important gap between the UV and soft X-ray regions, both in terms of wavelength and in terms of ionization states of key elements in the emission and absorption-line regions. The proposed observations will enable us to determine the physical conditions from a few to a few hundred Schwarzschild radii in two NLS1s and to compare these with the properties of other types of Seyfert 1s. ------------------------------------------------------------------------------ Prog ID: B063 PI: Boisse, Patrick Institution: Ecole Normale SuperieureDEMIRM Title: Probing the very small scale structure (l simeq 30 AU) in the interstellar medium (continued) We propose to extend our study of the very small scale structure in the molecular, atomic and ionized phases of the interstellar medium initiated during cyle 1 to larger scales (l simeq 30 AU) by taking two additional spectra of the runaway O star HD 34078. HD 34078 (AE Aur) moves at a transverse velocity of 103 kms (or 20 AU/yr); thus the 3 spectra which will be obtained during cycle 1 will allow us to sample adjacent lines of sight distant by simeq 10 and 15 AU at the cloud distance. The two spectra we propose to acquire during cycle 2 will allow to probe separations up to 30 AU and better characterize the column density fluctuations for a broad range of species, including H_2, HD, CO, CI, SI, SiII, CII, FeII ... Presently, only the first cycle 1 spectrum has been taken. It is excellent (SN simeq 20 at 1100 AA); HD lines are clearly detected as well as many lines from highly excited levels of H_2 (v=1, J=0, 1, 2, 3, 4 and v=0, J=9). From the analysis of this superb spectrum, we find that prospects are extremely encouraging for i) detecting variations deltaNN as low as a few H_2 (J=0, 1, 2) or weaker, nearly optically thin lines and ii) performing a very detailed modelling of this line of sight and of the physical conditions in the foreground gas. ------------------------------------------------------------------------------ Prog ID: B065 PI: Shrader, Chris Institution: NASA Goddard Space Flight Center Title: Far-UV Spectroscopy of X-Ray Novae We propose to obtain Far-UV spectroscopic observations of X--Ray Nova events selected on the basis of their optical--UV brightness and absorption characteristics. A recent case, XTE J1118+480, represents an excellent candidate to achieve our goals if it remains (or becomes) active during FUSE Cycle-2. This program, if approved, will be executed in coordination with related ToO programs utilizing the Rossi X-Ray Timing Explorer and the Hubble Space Telescope. Specific goals for FUSE include simultaneous measurement of the ionizing X-ray flux and the strengths of O 6 , ion C 3 , and ion N 3 lines. These measurements can then be applied as density, temperature, optical depth, and abundance diagnostics within the context of photoionization model calculations. In addition, we will search for variability on time scales of seconds, resulting, for example, from reprocessing of an X-ray flare in an accretion disk. ------------------------------------------------------------------------------ Prog ID: B066 PI: Brown, Thomas M. Institution: NASA/GSFC Title: The Hot Stellar Population and Cooling Flow of M87 We propose FUSE observations of M87, the central giant elliptical galaxy of the Virgo Cluster. These data will investigate two important questions in extragalactic astrophysics bullet What is the origin of the excess UV light in M87 bullet Can we detect the warm gas that should be present in galaxy cluster cooling flows The UV upturn phenomenon is a key indicator of age and abundance in elliptical galaxies. It originates in a population of hot evolved stars that are only well-isolated in the far-UV. In quiescent elliptical galaxies, the UV optical flux ratio correlates strongly with the optically-determined metallicity of the cool stars. However, the UV upturn in active galaxies is systematically bluer than one would expect from their optically-determined metallicities. In the case of M87, its UV emission is four times greater than expected, although non-thermal emission from its active nucleus comprises only sim10 to this puzzle lies in the far-UV, where the diagnostics characterize the appropriate hot population. In Cycle 1, we will obtain FUSE spectra of three quiescent ellipticals. Cycle 2 observations of M87 would explore the origins of the excess UV light in active ellipticals. The Virgo Cluster contains the nearest X-ray bright cooling flow, which is centered on M87. As the hot intracluster gas cools from sim 10^7K to sim 10^5K, it should emit strongly in the O 6 lambdalambda1032,1038 doublet. Although X-ray observations provide strong evidence for the hot gas, the emission from the warm gas has not yet been detected in an intracluster cooling flow. Our observations will provide an important test of the cooling flow interpretation, as they will be much more sensitive to the O 6 emission than was possible with earlier far-UV missions. ------------------------------------------------------------------------------ Prog ID: B067 PI: Walter, Frederick M. Institution: SUNY, Stony Brook Title: The early evolution of the circumstellar environment of solar-like stars The UV spectra of the youngest cool stars, the classical T Tauri stars, are dominated by emission lines of molecular hydrogen (H_2), yet within a few million years the H_2 lines fade and the spectra take on the characteristics of the solar chromosphere and transition region. We propose to obtain the FUV spectra of four low mass pre-main sequence stars to study the early evolution of the circumstellar material. This sample fills in the observational gap between the T Tauri stars in the FUSE cycle 1 program and the ZAMS stars like AB Dor. We propose 4 targets 2 very young naked (diskless) T Tauri stars, one transition object with an inner hole in its circumstellar disk, and a classical T Tauri star. We have (or will soon get) UV spectra of these stars with the HST, and one star is our XMM spectroscopic target. ------------------------------------------------------------------------------ Prog ID: B068 PI: Harper, Graham Institution: University of Colorado Title: FUV Spectra of Non-Coronal Evolved Late-Type Stars Mass Loss, FUV Emission, and Fluorescence We propose a detailed analysis of the FUV photoionizing radiation that provides crucial input physics for mass loss studies, e.g. observations of the flux below 1044AA will allow us to constrain the CaII/CaIII balance and make significant progress beyond previous optical studies on stellar mass-loss, and circumstellar photochemistry. In particular we seek to determine the relationship between the FUV radiation field and other more readily observable (archival HST or IUE) UV diagnostics. This will allow us to achieve our goal of empirically estimating the FUV radiation field for the vast majority of stars, which are too faint to be observed with FUSE, and to improve upon their uncertain mass-loss rates. The HLybeta profile provides crucial information on the excitation and ionization of hydrogen. HLybeta also causes fluorescence at longer UV wavelengths. We hope to establish directly the relationship between HLybeta and the fluorescent emission in the UV. We propose deep exposures of gammaCru (M3III), betaGru (M5III), and lambdaVel (K5Ib) that are well studied in other spectral regions and are important for the study of mass loss. These spectra will provide a valuable complement to the spectral-types and evolutionary phases of the GTO targets and our Cycle 1 target alphaTrA (K3II). ------------------------------------------------------------------------------ Prog ID: B069 PI: Dinerstein, Harriet Institution: University of Texas at Austin Title: Nebular UV Absorption Lines in Planetary Nebulae We propose to continue our Cycle 1 program of studying the Lyman and Werner bands of H_2, seen in absorption against the UV continua of planetary nebula central stars, which arise within neutral-molecular envelopes surrounding the ionized gas. These are the pump lines for a fluorescent cascade of near-infrared emission lines which are observed in many planetary nebulae. By observing the UV lines we can probe the chemical and thermal structure of the envelopes, as well as measure molecular column densities and clarify the excitation processes for the infrared lines. In Cycle 1 we were granted time for three targets, one of which was successfully observed shortly before submission of this proposal. Although the data were not yet available for examination, similar target observed by the project team revealed a rich set of H_2 circumstellar absorption features, demonstrating the feasibility of our program. FUSE spectra also include absorption features from atomic species such as O I and C II, which give rise to important far-infrared fine-structure cooling lines that likewise have been observed from planetary nebulae. In Cycle 2, we add as a secondary goal a search for nebular components of the O VI 032, 1038 AA absorption lines, which trace the presence of hot shocked gas, in nebulae with anomalously strong optical recombination lines of ions of oxygen and nitrogen. This will test a plausible hypothesis for the origin of this anomaly. ------------------------------------------------------------------------------ Prog ID: B070 PI: Sion, Edward Institution: Villanova University Title: Physics of Boundary Layers/White Dwarf Accretion in Dwarf Novae The central accreting object in compact binaries and other accreting systems is usually hidden from direct observation, enshrouded by optically thick accretion disks which are opaque to the radiation emitted by the central object as it accretes matter. In the dwarf novae RX And, WZ Sagittae and VW Hydri the underlying white dwarf accreter is clearly exposed with HST in the far UV, during quiescence. However, there is an unidentified second hot component in these systems. Since the hot white dwarf photospheric continuum is turning down, the contribution from a hotter inner disk region/boundary layer, accretion belt, or corona will show up in the FUSE wavelength regime. FUSE spectroscopy will deliver the following fundamental information: (1) delineation by profile shape and velocity, of lower temperature line formation regions associated with the rotating photosphere of the white dwarf from line formation region(s) of higher temperature ion species associated with a boundary layer/accretion belt (or putative hot corona?) still present surrounding the white dwarf; (2) white dwarf rotation rates, yielding critical information on the boundary layer temperature/structure and spinup of the white dwarfs by accretion; (3) detection of metal line profiles of the most abundant element, C, and also N in WZ Sagittae to test accretion versus dredgeup for the origin of carbon, and test physical mechanisms that control the flow of accreted elements and hence abundance changes (diffusion, mixing, dilution, dredeup and ongoing accretion during quiescence). ------------------------------------------------------------------------------ Prog ID: B071 PI: Cartledge, Stefan I.B. Institution: Northwestern University Title: Anomalous Oxygen and Krypton Abundances in Interstellar Gas We propose to obtain FUSE observations of interstellar ionH1 and H_2 absorption toward 10 stars observed by STIS as part of the ISM SNAP Survey, a Cycle 8 HST observing program. The ISM SNAP Survey was designed to produce a database of high quality, high resolution spectra from which gas-phase abundances for large portions of the Galaxy could be derived. Krypton and oxygen have been chosen during initial analysis as tracers of the amount of absorbing material along the various sightlines. The gas-phase oxygen and krypton abundances relative to total hydrogen column density have previously been shown with GHRS to be essentially constant in the local Milky Way. Further, krypton is a noble gas not expected to be depleted much into dust in the ISM. The ISM SNAP Survey has extended precision measurements of these elements to significantly higher column densities than GHRS. Intriguingly, several Survey sightlines have yielded anomalously high Kr 1/ O 1 and O 1/H 1 ratios. By measuring the total hydrogen column density along these 10 sightlines, it will be possible to better determine the nucleosynthetic and/or dust depletion implications of these anomalies. ------------------------------------------------------------------------------ Prog ID: B072 PI: Ayres, Thomas Institution: University of Colorado Title: Magnetospheres and Winds in the Rapid Braking Zone FUSE exposures of five late-Fearly-G giants will probe fundamental plasma dynamics in their hot magnetized outer atmospheres; as encoded in spectral line widths, Doppler shifts, broad components, asymmetries, and wind-induced circumstellar absorptions. The giants lie in or near the Rapid Braking Zone where moderate mass stars undergo a radical transformation of their coronal outer atmospheres. We also will explore the even more extreme extension of the RBZ to higher masses two G0 supergiants in the so-called hybrid region where hot coronae mix freely with cool stellar winds. FUSE \/ spectra of the key O~VI $\lambda$1032 and CIII lambda977 features will allow us to separate the influences of temperature and opacity on the super-rotational broadening of the RBZ subcoronal emissions; and will strongly complement an ongoing HST STIS (1150--3100 A) survey of late-type stars. Our ultimate objective is to understand stellar magnetic activity; crucial to solar-terrestrial relations, the early evolution of solar system, and one face of a myriad of hydromagnetic phenomena that occur in many cosmic environments protostellar envelopes, neutron star magnetospheres, the accretion disks of cataclysmics, and those of AGN. The dramatic, rapid magnetic evolution of the RBZ stars allows us to view many fundamental aspects of stellar activity---coronal structuring, heating, and angular momentum loss---from an entirely different perspective than afforded by the highly accessible---but singular---case of our Sun. It is through these different perspectives that we can hope to gain new insights into the underlying physical processes. ------------------------------------------------------------------------------ Prog ID: B074 PI: Raymond, John Institution: CfA Title: Molecular Hydrogen in the Quiescent Disk of SW UMa Disk-instability models, which are usually invoked to explain the outbursts of transient close binaries, predict that the gas in the quiescent disks of Dwarf Novae and X-ray Transients should be neutral. In fact, if the reduced viscosity of the low state results from the disappearance of MHD turbulence as predicted by the Balbus-Hawley instability, the required ionization state is so low that the gas should be molecular. There is currently no direct observational evidence for this. We propose a spectroscopic observation of the Dwarf Nova SW UMa, in an attempt to detect the molecular hydrogen bands at 1060 and 1105 AA in the quiescent disk of this system. H_2 band diagnostics could provide valuable information on the ionization fraction of the gas which is essential for determining the nature of viscosity in the disk. ------------------------------------------------------------------------------ Prog ID: B075 PI: Raymond, John Institution: CfA Title: Particle Acceleration in SN1006 Shock Waves We will attempt to measure the fraction of a shock waves energy that goes into cosmic rays. The NE sector of the young SNR SN1006 shows strong non-thermal X-ray and gamma ray emission. The Hopkins Ultraviolet Telescope observed the pure Balmer line filament in the NW section of the young supernova remnant SN1006. The observation demonstrated that the electrons and ions do not reach temperature equilibrium in this 2300 kms collisionless shock. However, the NW section of SN1006 shows very little non-thermal emission at radio or X-ray wavelengths. We propose to obtain the line widths, intensities and spatial brightness profiles of the O VI lines in sections of the NW and NE shock waves to compare the electron-ion and ion-ion temperature equilibration efficiencies in shocks with very strong and very weak non-thermal X-ray and radio emission. If a substantial fraction of the energy dissipated in the shock goes into cosmic ray acceleration, the line profile in the NE shock will be narrower. ------------------------------------------------------------------------------ Prog ID: B077 PI: Guinan, Edward F. Institution: Villanova University Title: The Cosmic Distance Scale An Accurate Distance to the LMC Using Eclipsing Binaries The distance to the LMC is crucial to calibrating the cosmic distance scale but remains controversial and uncertain despite the efforts of many investigators. We have demonstrated that the analysis of eclipsing binaries (EBs) has the potential to resolve this controversy. Guinan et al. (1998, ApJ, 509, L21) and Fitzpatrick et al. (2000, BAAS, 196, 2806) analyzed ground- and space-based observations of HV2274 and HV982 and determined LMC distance moduli of V-M v circ 18.30 0.07mag and V-M v circ 8.32 0.10mag, respectively. Such an excellent agreement demonstrates the potential of this method, and the suitability of EBs as accurate standard candles. However, these are only results for two stars and the method must be verified with additional observations and extended wavelength coverage into the Far-UV where the stars strongly radiate. The primary goals of the FUSE observations are to secure accurate, definitive temperatures and interstellar extinctions to the target stars (Sp. Typ. O7-B2), whose energy maxima occurs in the FUSE spectral range. All of the targets have FOSSTIS spectrophotometry covering 1150--4820AA. The FUSE observations will be combined with UVoptical spectrophotometry and with light and radial velocity data that will yield the radii, T_ eff, E(B-V), log g, and FeH of the stars. The distances to the stars (and the LMC) are directly determined from their radii, temperatures and apparent brightnesses (flux received at Earth corrected for ISM extinction). The FUSE observations, when combined with our other datasets, will reduce the uncertainty of the LMC distance to better than 2-3%. ------------------------------------------------------------------------------ Prog ID: B078 PI: Guinan, Edward F. Institution: Villanova University Title: The FUV Sun in Time A Study of Solar Analogs of Different Ages We propose to use FUSE to complete an in-depth study of the evolution of the transition region and low corona of a solar-mass star throughout its main-sequence lifetime. This program is part of a comprehensive study of the Sun in Time across the electromagnetic spectrum. We have defined a homogeneous sample of single G0-5V stars with well-known rotation periods that are proxies of the Sun at different ages. We are studying the dynamics of the lower layers of the stellar atmospheres by investigating line shifts, line asymmetries, and line broadenings that we presume are related to chromospheric evaporation by high-energy processes identified in the overlying corona. Emission measure and temperature analysis will allow us to obtain a complete -D atmospheric model of active regions that we will link to the previously obtained coronal X-ray data. We will infer transition region pressures through the powerful density-sensitive ratio of the Csc iii 977AA1176AA lines; this important diagnostic will be adequate to identify and model the relevant magnetic structures based on the solar analogy, and, together with our coronal X-ray (XMM, ROSAT, ASCA, SAX), EUV (EUVE), and TR (IUEHST) data, to infer the importance of coronal energy releases. Our FUSE investigation is central to the understanding of the evolution of magneto-dynamic atmospheric phenomena, and the associated high-energy emissions in the Sun and in solar-type stars. It also bears on the crucial question of the influence of the young Suns expected strong FUV emissions on the developing planetary system -- particularly on the erosion of Mars primitive atmosphere. Coordinated contemporaneous observations (with XMM, Chandra, HST, optical photometers, partly from guaranteed time programs) are planned and will be organized. ------------------------------------------------------------------------------ Prog ID: B079 PI: Gibson, Brad Institution: Swinburne University Title: Fossil Fuel in the Local Group We propose a direct observational test of the Local Group Infall hypothesis that the majority of High-Velocity Clouds (HVCs) are the extragalactic building blocks of the Local Group. The line of sight to the Seyfert PG1011-040 fortuitously passes through HVC,246+39+125 in the Wannier Clouds, a collection of HVCs in the direction of the Local Group anti-barycenter. The proposed FUSE Cycle2 observations will be used to constrain the metallicity and ionization properties of HVC,246+39+125, which in turn will reveal its local (higher metallicity) or extragalactic origin. Unlike the HVCs currently under study by the FUSE PI Team (eg, Magellanic Stream, Complexes A, C, and M), HVC,246+39+125 is expected to lie at a distance >~ 400,kpc, be of low intrinsic metallicity, and reside in the M31--Milky Way filament predicted by the BlitzSpergel Local Group Infall model. None of the Galactic HVCs being studied by the FUSE PI Team have these same a priori predictions, and thus our program provides a natural complement to the more general PI programs. ------------------------------------------------------------------------------ Prog ID: B081 PI: Blair, William P. Institution: Johns Hopkins University Title: A Study of Hot Gas in Shock Wave--Interstellar Cloud Interactions We will use FUSE to obtain detailed information about the kinematics, resonance line scattering properties, and physical conditions of gas involved in the collision of the Cygnus Loop supernova blast wave with an interstellar cloud. The region, known as XA, is located on the eastern side of the supernova remnant and a wealth of supporting information at optical, UV, and X--ray wavelengths is available. High resolution line profiles for CIII lambda 977, NIII lambda 989.8, and OVI lambdalambda1032,1038 (and possibly many other lines) will be used to sort out the competing effects of turbulence, thermal instabilities, projection effects, and resonance line scattering at several key locations on and ahead of the core of the shocked cloud. Investigating such interactions is of primary importance for understanding SNR evolution in a cloudy medium and for assessing the effectiveness of SNR shock waves in heating and mixing the ISM. ------------------------------------------------------------------------------ Prog ID: B082 PI: Froning, Cynthia Institution: Space Telescope Science Institute Title: FUSE Observations of the Bright, Eclipsing Novalike Cataclysmic Variable, UXUMa Novalike cataclysmic variables (NL CVs) are high mass-transfer rate, disk-fed CVs. The high mass flow rate keeps their disks in a steady state, making NLs among the simplest accreting systems to understand and excellent laboratories for the application of sophisticated accretion models. FUSE is ideally suited to address one facet of accretion theory that remains poorly understood the structure and driving mechanism of accretion disk outflows. Outflows in CVs take the form of fast bipolar winds. The mechanism that drives the wind, the influence of disk and boundary layer photons andor shocks on the wind, and the thermal and ionization structure of the wind are not well known. We propose to use FUSE to obtain orbital phase-resolved FUV spectra of UXUMa. UXUMa is the brightest of the eclipsing NLs and observations of this system have driven much of the ground-breaking research on wind and accretion disk theory in CVs. We will model the variations in the FUV wind line profiles over the binary orbit to characterize the structure and geometry of the wind and probe the link between the wind and the disk. Modeling changes in the lines and continuum before, during, and after the eclipse will allow us to separate the relative contributions of the different FUV emitting (and absorbing) components in the binary---including the winds, disk, and boundary layer. In addition to characterizing outflows, FUSE observations of UXUMa will facilitate modeling of the underlying accretion disk and the disk-boundary layer physics in cataclysmic variables. ------------------------------------------------------------------------------ Prog ID: B084 PI: Luttermoser, Donald G. Institution: East Tennessee State University Title: The Outer Atmosphere of Mira Variables We propose to use FUSE to probe the temperature-density structure of the shocked atmospheres of long-period variable (Mira-type) stars. For the first time, FUSE gives us the capabilities to study the outer shocked region of the atmosphere using the hydrogen Lyman lines. At 5 separate phases, we wish to obtain MDRS spectra of the Lyman series from Lybeta to the Lyman limit (1030AA --- 912AA) for the warm Mira star, SCar. With these spectra, we will make comparisons (1) between Lyman flux (and possibly H_2 emission) variability and the variability in the UV emission lines and hydrogen Balmer lines using previously obtained HST HRS, IUE, and ground-based optical spectra at coincident phases to the FUSE observations to study the effect that the radiation field from the lower, hotter shocks (where Mg 2 and the Balmer lines form) have on the upper shocked region (where the Lyman lines form), and (2) to synthetic spectra from representative dynamic models we have generated. These NLTE radiative transfer calculations have shown that the radiation field of the inner shocks dominate the ionization throughout the entire atmosphere. The calculations also have shown that the Lyman emission lines form in the outer reaches of the atmosphere where the shocks are much weaker as they propagate outward. This is the first time such a diagnostic has been measured for the outer atmosphere of these stars. It also gives us a pioneering attempt to record the suspected strong FUV H_2 in emission. Such an observation will have strong constraints on the atmospheric structure of the outer layers of these stars. Finally, it is imperative to obtain fairly high dispersion (R approx 10,000) spectra of the Lyman lines in Miras, since these lines are fundamental in the understanding of the energy flow in their outer atmosphere, and of mass loss in this critical stage of a stars evolution. ------------------------------------------------------------------------------ Prog ID: B085 PI: Cheng, K.-P. Institution: California State University, Fullerton Title: beta Pic-like Circumstellar Gas Disk Around 2 And Ultraviolet observations of 2Andromedae with the Goddard High Resolution Spectrograph onboard the Hubble Space Telescope (HSTGHRS) clearly reveal the existence of circumstellar gas as well as the interstellar gas along the line-of-sight toward this nearby star. We also detected varying red-shifted CaII absorptions in our ground-based optical spectra, which we interpret as gaseous infall. These variable CaII absorption features and the presence of circumstellar absorption from AlIII lambdalambda1854.716,1862.790 and excited fine-structure levels of FeII near 2600 AA in our HSTGHRS data of And are similar to those observed in the proto-planetary system candidate betaPictoris. However, unlike betaPic, 2And has no detectable IR excess based on our previous IRAS survey of dust disks around nearby A stars. The detection of gaseous infall with characteristics similar to betaPic in an apparently dust-free stellar system suggests that we should re-examine existing models that attempt to explain the gaseous infalls in betaPic with grazing comets or erosion from the surrounding extensive dust disk. FUSE observations of 2 And will allow us to study the characteristics and origin of the circumstellar gas. Our results will provide insight into the link between the circumstellar gas and dust. ------------------------------------------------------------------------------ Prog ID: B086 PI: Clayton, Geoffrey Institution: Louisiana State University Title: Far-Ultraviolet Interstellar Extinction in the Large Magellanic Cloud Understanding interstellar dust and its role in the universe is very important. Virtually all observations of astrophysical objects and their physical processes are affected by the presence of dust either within the system being studied or along its line of sight. We propose a research program that will significantly improve our knowledge of dust properties, specifically those of small grains. Such an advance has not been possible prior to the advent of FUSE and its unique capabilities the high far ultraviolet (FUV) throughput and the ability to resolve H_2 lines, combined with a well-characterized instrumental calibration. We will derive FUV extinction curves for several types of sightlines which possess distinct signatures associated with the small grain population and whose mid-UV extinction curves reveal vastly differing amounts of intermediate-sized particles. We will study sightlines in the Large Magellanic Cloud where very non-Galactic mid-ultraviolet extinction properties are seen. A new analysis of the mid-ultraviolet extinction found a region near the supergiant shell LMC2 where the 2175 A bump is very weak. LMC sightlines inside and outside this region will be sampled with FUSE. These data will be used to probe and constrain the properties of the small dust grains, such as abundance and size, and their connection to the very different environments observed. ------------------------------------------------------------------------------ Prog ID: B087 PI: Prochaska, Jason X. Institution: Carnegie Observatories Title: Physical Properties of a z ll 1 Lyman Limit System One of the most exciting aspects of quasar absorption line studies is to test and constrain theories of galaxy formation and evolution. A principal challenge to this quest is to obtain coincident knowledge of the physical properties of the absorbing gas and the host galaxies or large-scale structure. We propose to analyze the physical properties e.g. metallicity, ionization state) of the z0.167 partial Lyman limit system towards PKS0405-12. By synthesizing our investigation of the physical properties of this QAL system with the galaxy data we have obtained we will compose an unprecedented study of a low redshift QAL system. FUSE observations are essential for an accurate HI column density of this system as well as measurements of its metallicity, ionization state, and relative abundances of C, S, Si, and Fe. This detailed examination of a z sim 0 QAL system when combined with our knowledge of the absorbing galaxies will provide a benchmark for comparisons against high redshift systems, pose questions on the nature of halointragroup gas, and advance our understanding of OVI absorbers. ------------------------------------------------------------------------------ Prog ID: B089 PI: Welty, Daniel E. Institution: University of Chicago Title: Abundances and Physical Conditions in the SMC ISM We propose to obtain far-UV spectra of two stars in the SMC, as part of a detailed study of the interstellar medium in the Magellanic Clouds. Together with optical andor near-UV spectra obtained at higher resolution and SN, these far-UV spectra will be used to determine accurate abundances, pressures, temperatures, densities, and radiation fields for both neutral and ionized clouds in the SMC and in the Galactic disk and halo. Because of the low metallicity, low dust-to-gas ratios, and strong radiation fields in the SMC, the derived properties of the SMC clouds will provide valuable tests for theoretical models of interstellar clouds. Determining detailed abundancesdepletions and physical conditions for diverse environments in our Galaxy and in the Magellanic Clouds will also aid in understanding the absorption-line systems seen toward distant QSOs. ------------------------------------------------------------------------------ Prog ID: B090 PI: Shull, Michael Institution: University of Colorado Title: Molecule Formation at High Extinction and Low Metallicity in the Magellanic Clouds The fundamental physical and chemical processes at work in molecular clouds are key objects of FUSE science. Preliminary results on h2 in the LMC, based on available PI Team data, suggest a reduced molecular fraction in the low-metallicity LMC gas. Although this result provides the first direct evidence of a metallicity dependence in the formation rate of interstellar h2, the available FUSE targets do not sample the high-extinction regime where the correlation between E(B--V) and molecular fraction is strong. Therefore, we cannot test whether the apparent reduction in molecular fraction is due to reduced formation rates, high radiative destruction rates, or selection effects. We propose observations of 7 LMC stars and 2 SMC stars with E(B--V) 0.20 -- 0.42, which will allow us to test cloud models that incorporate different assumptions about the formation rate of h2 as a function of metallicity. We will also obtain CO emission maps in these selected regions to assess the COh2 ratio in this gas. As a key goal of FUSE h2 science, this test can be applied only to sight lines for which the variation of molecular fraction with extinction can be tightly controlled. ------------------------------------------------------------------------------ Prog ID: B091 PI: Jura, Michael Institution: University of California, Los Angeles Title: Search for Molecular Hydrogen Around Vega-type Stars Giant planets are believed to form in the disks of gas and dust surrounding young stars. However, CO surveys of dusty Vega-type stars have found little gas. In an effort to understand the dissipation of molecular gas in young debris disk systems, we propose to conduct a spectroscopic search for absorption in the Lyman and Werner series of H_2 surrounding the Vega-type stars sigma Her, HR 7188, HR 3314, alpha CrB and HR 4796. Observations of these absorption features with FUSE will provide an extremely sensitive test for the existence of circumstellar molecular gas. We have selected sources for study with the FUSE prime spectrograph which have not been reserved by the FUSE PI teams and 1) contain dusty debris disks indicative of youth. (2) lie within 100 pc of the sun. (At such close distances, the amount of interstellar gas should be minimal.) (3) emit enough ultraviolet photons to be useful to detect H_ 2 in absorption. ------------------------------------------------------------------------------ Prog ID: B094 PI: Morse, Jon A. Institution: University of Colorado Title: Excitation and Abundances in N132D We propose to obtain fuse far-UV spectroscopic observations of the shocked outer rim of the young, oxygen-rich supernova remnant N132D in the LMC. These data will be used to calibrate the relative contribution of OVI emission from the blastwave expanding into the ambient ISM in our previous fuse spectrum of the ejecta in N132D. In addition, the fuse spectra will be combined with existing and proposed hst and chandra imaging and spectroscopic data to completely characterize the excitation of the outer blastwave. ------------------------------------------------------------------------------ Prog ID: B097 PI: Dewdney, Peter E. Institution: National Research Council of Canada Title: Diffuse Molecular Hydrogen in the Galactic Plane As part of a high-resolution multiwavelength survey of interstellar matter in the Galactic plane, we are investigating the physical state of cold diffuse interstellar matter traced by dust, HI self-absorption, and various molecular species. An increasing body of evidence from our survey and others suggests that far-IR emission and H 1 self-absorption may trace a significant amount of molecular hydrogen which lacks traditional proxy tracers like ^12CO. Far-UV spectroscopy of these clouds will provide the first direct measure of their molecular hydrogen content. We have selected a set of stars with foreground dust but no detected CO emission to observe with FUSE. All of these probe the molecular content of dusty diffuse environments, with some also sampling ionH1 self-absorption features. Obtaining H_2 column densities for these clouds is essential for understanding their physical properties, structure, and evolution, as well as the larger role of the cold diffuse medium in star formation and the Galactic ecosystem. ------------------------------------------------------------------------------ Prog ID: B101 PI: Barrett, Paul Institution: Space Telescope Science Institut Title: Time-resolved spectroscopy of high field polars A long sought-after group of polars are those with high magnetic field >60 MG), because they may provide valuable clues to the structure and dynamics of accretion in strong magnetic fields and the evolution of CVs in general. The discovery of several soft X-ray polars by ROSAT and their subsequent identification as high field polars supports the conclusion that the bremsstrahlung is suppressed at higher fields and cyclotron cooling predominates. We propose time-resolved FUV spectroscopy of high field polars to study their accretion kinematics, their high excitation lines (e.g. OVI, OIV, and SiIV), and the distribution of gas in the binary. ------------------------------------------------------------------------------ Prog ID: B104 PI: Long, Knox Institution: Space Telescope Science Institute Title: Density, Velocity and Ionization Structure in Accretion-disc Winds We propose to exploit the unique capabilities of it FUSE to monitor variations in the wind-formed spectral lines of 3 luminous, low-inclination, cataclysmic variables (CVs). Our principal goal is to improve our understanding of the dynamics of accretion-disc winds. We have previously used HST to investigate substantial and rapid (sim hours to minutes) variability in our target stars, BZ Cam, RW Sex and V603 Aql, and have demonstrated that their disc-outflows are highly structured. We aim here to follow up our discoveries by securing FUSE time-series data. These observations will allow us to determine the relative roles of density and ionization state changes in the outflow and to search for spectroscopic signatures of stochastic small-scale structure and shocked gas. By monitoring the temporal behavior of blue-ward extended absorption lines with a wide range of ionization potentials and excitation energies, we will track the changing physical conditions in the outflow. A new sophisticated Monte Carlo code will be used to calculate the ionization structure of and radiative transfer through CV winds. This will allow us to establish the wind geometry, kinematics and ionization state, both in a time-averaged sense and as a function of time. Our FUSE observations will provide a legacy that will be fundamental to the development of dynamical models of accretion-disc-driven winds, permitting critical tests of recent hydrodynamic simulations of unstable, line-driven disc winds. ------------------------------------------------------------------------------ Prog ID: B105 PI: Leighly, Karen Institution: The University of Oklahoma Title: Wind Emission in Narrow-line Seyfert 1 Galaxies Narrow-line Seyfert 1 galaxies (NLS1s) are known to have characteristically different X-ray properties than Active Galactic Nuclei (AGN) with broad optical lines. The most promising explanation for this behavior is that NLS1s have a higher accretion rate with respect to Eddington. This result is fundamental, since accretion is thought to be the ultimate power source for all AGN. Our recent HST spectra from two NLS1s reveal unusual UV emission line properties. The high-ionization lines are broad and strongly blueshifted, in contrast with the low-ionization lines which are narrow, centered at zero velocity, and symmetric. The most plausible explanation is that the high-ionization lines are emitted by a wind and the low-ionization lines are emitted by a disk. Such models have been discussed previously, but our spectra provide perhaps the strongest evidence to support these models to date. We now seek to understand the geometry and physical conditions in the wind. The proposed FUSE observations of two NLS1s, 1H0707-495 and IRAS13224-3809, will allow us to examine the profile of the high ionization resonance line ionO6lambda1034. This line is typically emitted in material with higher ionization parameter than the lines observed in our HST spectra and thus comparison of the O 6 and ion C 4 line profiles will allow us to distinguish between classes of models that do and do not predict ionization stratification. These targets are particularly suited for this investigation since only a few objects are known that have high-ionization lines dominated by wind emission. ------------------------------------------------------------------------------ Prog ID: B106 PI: Bregman, Joel Institution: University of Michigan Title: The Supernova Heating Rate in Spiral Galaxies In spiral galaxies, supernovae dominate the energy input into the ISM, controlling the volumes of hot and cold gas, the pressure, and star formation itself. Previously, the heating rate was estimated from the supernova rate and the energy per supernova, the product of which is uncertain to half an order of magnitude. FUSE provides a direct, accurate, and independent measure of the heating rate because the shocked gas emits O 6 as it cools through the 3times10^5 K regime. With the large aperture, we propose to measure the ionO6 emission from spiral arm and interarm locations for 4 nearby normal galaxies. Ultimately, measurements of ionO6 may prove as important as studying ionH1 or molecular gas in spiral galaxies. ------------------------------------------------------------------------------ Prog ID: B107 PI: Crenshaw, D. Michael Institution: Catholic University of America Title: Monitoring the Variable Absorption in the Seyfert 1 Galaxy NGC 3783 with FUSE, HST, and Chandra More than half of all Seyfert 1 galaxies show intrinsic UV absorption lines and X-ray warm absorbers. The frequent occurrence of this phenomenon suggests that photoionized, warm absorbing gas is an important component of the nuclear structure of AGN. To understand the nature and origin of this gas, we must know its location, physical conditions, and kinematics. By simultaneously monitoring the variability of the absorption at UV and X-ray wavelengths, we can determine the radial location, density, and ionization state of the absorbing gas and measure its evolution in ionization, column density, velocity, and coverage of the active nucleus. NGC 3783 is an ideal target for such a study due to its brightness, and its extremely variable absorption and rapid continuum variability in both the UV and the X-rays. FUSE is a crucial tool for our work since the high-order Lyman lines provide an accurate measure of the neutral hydrogen column, and the high-ionization sc Ovi lines provide a key link between the UV and X-ray absorbing gas. ------------------------------------------------------------------------------ Prog ID: B108 PI: Sankrit, Ravi Institution: Johns Hopkins University Title: Investigation of Supernova Remnant Shocks in the Vela-Puppis Region We propose to use FUSE to observe ultraviolet emission spectra of supernova remnants (SNRs) in the Vela-Puppis region. With its sensitivity to emission from extended sources, its spatial resolution and its particular wavelength coverage, FUSE is an excellent instrument for such a study. The FUSE bandpass includes CIIIlambda977 and OVIlambdalambda1032,1038, which are strong lines in SNR shocks and trace low ionization and high ionization gas respectively. The spectral resolution of FUSE will allow us to compare line profiles and study the kinematics of the post-shock flow. Since the OVI doublet is well separated, we will be able to use the flux ratio between the lines to estimate the amount of resonance scattering present. We will also be able to detect the presence of multiple components if they are sufficiently well separated in velocity space. In addition to these strong lines, we expect that several lines such as SVIlambdalambda933,944 and NIIIlambda991 will provide additional constraint on models. ------------------------------------------------------------------------------ Prog ID: B109 PI: Bergvall, Nils Institution: Uppsala astronomical observatory Title: The Lyman break in the luminous BCG Haro 11 Deep galaxy surveys have indicated that luminous starburst dwarfs may play an important role in explaining the increasing star formation activity towards higher redshifts. The relatively low masses and high star formation efficiency of these galaxies allows for a significant leakage of Lyman continuum photons into intergalactic space. They may therefore play an major role in the reionization of the universe at early epochs. To assess the importance of these objects in this respect we want to use FUSE to study, as a first step, one local luminous blue compact galaxy with extreme starburst properties, Haro 11. When compared with similar galaxies, Haro 11 is remarkably devoid of HI. This may be understood if a major part of the ISM is ionized by the starburst or is in molecular form. We propose to use FUSE to measure the strength of the Lyman continuum break to estimate the amount of Ly-continuum photon leakage and seach for molecular absorption lines of diffusely distributed H_2 to determine or set upper limits of the column density. ------------------------------------------------------------------------------ Prog ID: B110 PI: Werner, Klaus Institution: Universitat Tubingen Title: Iron abundance in the WC-PG1159 central star of Abell 78 The very first attempt to measure the iron abundance of a hot H-deficient post-AGB star arrived at a surprising result. Based on the absence of Fe lines in a FUSE spectrum of the PG,1159-type central star of the planetary nebula K1-16 we could show that this object is Fe-deficient by a factor of at least 10--100. The same might be true for two other PG1159 central stars with similar stellar parameters based on IUE spectra, but firm results have to be waited for until FUSE spectra are acquired (PI team targets). Here we propose to look for iron lines in the central star of Abell78, which is of spectral type WC-PG,1159, hence, it is an immediate progenitor of the PG,1159 stars. We intend to see if the Fe-deficiency can be traced back in evolution closer towards the AGB phase. If this is the case then the Fe-deficiency might be caused by dust fractionation on the AGB, hence, it is caused by the same phenomenon which is responsible of the extreme Fe-deficiency found in some (H-rich) early post-AGB stars. ------------------------------------------------------------------------------ Prog ID: B112 PI: Andersson, B-G Institution: Johns Hopkins University Title: Molecular Hydrogen Fluorescence in IC 63 FUV radiation shortward of 1108 AA causes electronic excitations of the hydrogen molecule through the Lyman (B-X) and Werner (C-X) transitions. The relaxation back to the electronic ground state gives rise to a rich fluorescent spectrum. Under favorable conditions this spectrum can be observed. We propose to observe this fluorescence at unprecedented resolution and sensitivity in the reflection nebula IC 63. Earlier observations suffered from restricted wavelength coverage or lack of spectral and spatial resolution. Although the results are in general agreement with theory, distinct discrepancies persist, most notably a shortfall in the absolute intensity of the fluorescent flux by a factor of 10, compared to theoretical models, in the FUSE wavelength range. In order to provide a detailed test of existing models, we propose to acquire high quality data in three locations within the reflection nebula at different distances from the ionization front. By observing several locations and comparing the strength of the fluorescence, we will also be able to address the transfer of the continuum radiation through the nebula. ------------------------------------------------------------------------------ Prog ID: B114 PI: Murphy, Edward Institution: University of Virginia Title: Observations of O VI Emission in the Hot Halo of NGC 891 We propose to use fuse to search for ovi emission from hot, cooling gas in the halo of the well studied, edge-on spiral galaxy NGC891. Our proposed search for ovi emission in the halo of NGC891 will allow us to determine the total mass of transition temperature cooling gas (Tsim3times10^5 K), the scale height of the ovi gas, and to compare the distribution of this transition temperature gas with hotter gas (Tsim3times10^6 K) as revealed by ROSAT. We have selected 3 positions in the halo of NGC891 for exposures of 30 ksec each (90 ksec total). One position is sim 2.25 kpc above the nucleus of the galaxy to search for hot material escaping from the bulge. The remaining two positions are placed sim 1.5 and 2.5 kpc above an active star-forming region in the NE section of the disk. A similar fuse Cycle 1 observation of the strongly-interacting edge-on spiral NGC 631 produced a detection of ovi emission in 20 ksec. Since NGC 891 is not interacting with other large galaxies, it provides a better comparison with the halo properties of the Milky Way. ------------------------------------------------------------------------------ Prog ID: B119 PI: Holberg, Jay B. Institution: University of Arizona Title: A FUSE Search for Nitrogen and Carbon in Hot White Dwarfs We propose a FUSE investigation of presence of spectral lines due to the first and second ionization stages of carbon and nitrogen in the photospheres of hot DA white dwarfs. In general, knowledge concerning the presence of N and C is available only for the hottest stars (T_eff > 35000 K), from the C IV 1550 AA) and N V (1240 AA) resonance lines. In cooler DA stars, these lines are weakened and are difficult to observe, leaving few spectral lines longward of 1200 AA to indicate the presence of these important elements in the atmospheres of DA stars. With FUSE, we will measure the presence of N and C using the strong N II, N III, C II, and C III lines in the FUSE band pass. We will also use these lines to investigate and test models of the stratification of these heavy elements in the atmospheres of DA stars. ------------------------------------------------------------------------------ Prog ID: B120 PI: Holberg, Jay B. Institution: University of Arizona Title: Observations of the LISM with Hot White Dwarfs We propose FUSE observations of the interstellar lines of sight for a set of white dwarf stars. For each of these stars, the full ionization state of interstellar hydrogen and helium has now been measured. Using EUVE, we have determined the ionization fractions of H and He, and from STIS observations with HST, we have detailed knowledge of the velocity structure and composition for each of these lines of sight. We will use FUSE observations of these stars to complete our models of these unique lines of sight through the Local Interstellar Medium (LISM) by measuring ground state and fine structure transitions of Ar I, C II, C III, N II and N III ions which occur in the FUSE band pass. ------------------------------------------------------------------------------ Prog ID: B122 PI: Dupuis, Jean Institution: University of California, Berkeley Title: A Search for Trace Elements in Ultramassive White Dwarf Photospheres Ultramassive white dwarfs form a relatively large proportion of white dwarfs discovered during recent extreme-ultraviolet surveys of the sky. Their exact origin is unknown but it is believed that some of them might be white dwarfs with an oxygen-neon core resulting from the evolution of single star with an initial mass between 8 ltappeq M ltappeq 11 msun. Another possibility is that these may be the result of the merger of two normal mass white dwarfs (Msim 0.6msun). The surface composition of ultramassive white dwarfs is likely to be sensitive to their formation scenario. We propose to observe 2 of the brightest known ultramassive white dwarfs with fuse to search for presence trace elements (mainly C, N, O, Si, S, P, and Fe). We plan on using non-LTE synthetic spectra of white dwarfs to model the profiles of Lyman lines and measure or set upper limits on abundances of trace elements with resonance lines in the fuse range. These sources are also excellent background sources to investigate the local interstellar medium and we plan on measuring column densities of detected interstellar absorption lines. ------------------------------------------------------------------------------ Prog ID: B126 PI: Espey, Brian Institution: Space Telescope Science Institute Title: Symbiotic Binaries Laboratories for wind studies Symbiotic binaries are ideal objects to study the mechanism of stellar wind formation. From analysis of the collision of the white dwarf and red giant winds, we can determine how the wind reacts to differences in stellar parameters. This is vital to understanding the mechanism of wind formation and to testing line-driven wind theory. Unlike massive binaries, the winds of a symbiotic system have very different characteristics -- the hot wind is very thin and fast, whereas the cool wind is slow and weakly ionized -- and hence they can be isolated spectroscopically. In addition, the white dwarf secondary of the symbiotic systems provides a far-UV continuum source against which absorption from a broad range of ionization levels can be seen, ranging from molecular hydrogen surrounding the giant star to highly ionized material in the wind collision region. Because of the high ionization lines arising in the hot and shocked gas, as well as the molecular and atomic absorption arising in the red giants extended atmosphere, phase-resolved spectra provide the unique tomographic information we require to improve our knowledge of these systems and how winds are generated and interact. Based on our observations made during Cycle 1, we know that our proposal is technically feasible. ------------------------------------------------------------------------------ Prog ID: B127 PI: Gull, Theodore Institution: NASA/GSFC/LASP Title: Just What is Eta Carinae? Eta Carinae, when observed by FUSE during the Early Release Observations (ERO), was found to have surprisingly bright far ultraviolet fluxes clear down to 920\AA. Eta Carinae is a very massive star nearing the end of its lifetime and has undergone episodic outbursts. Over the past few decades, Eta Carinae has brightened continuously with a 5.5-year modulation in the visible and X-rays. What is the cause of the variability? Is Eta Carinae a single star or a binary system? Based upon the periodic variability, the hardness of the X-ray spectrum, and now the large UV flux measured by FUSE, we strongly suspect that Eta Carinae has a hot companion with a fast, massive wind. A 40 M\odot star could easily be the secondary companion of the >100 M\odot primary. Neither current radial velocity measurements nor visible spectroscopy would detect it. The FUSE spectral region offers the best opportunity of direct detection. In Cycle 2, we propose to observe Eta Carinae once early and once late in the cycle to look for variations in the stellar continuum, in the stellar line profiles and in circumstellar line absorptions. ------------------------------------------------------------------------------ Prog ID: B128 PI: Massa, Derck Institution: Raytheon ITSS Title: CNO Abundances in LMC BN and BC Supergiants We propose to observe 10 BN, BC and normal B1 Ia supergiants in the LMC. By matching normal and CNO peculiar stars, the stellar wind line data will enable us to determine the relative C, N and O abundances between the different groups. Finally, by employing a simple model for the origin of the CNO enhancements, it will be possible to derive absolute abundances for all of the paired stars. This information will enable us to address long standing questions concerning the origins of the BNBC phenomenon, and elucidate the latter stages of massive star evolution. Because our analysis requires unsaturated wind lines, only FUSE can provide access to C, N and O wind lines. Furthermore, all of these lines will be unsaturated only in stars near spectral type B1 Ia. ------------------------------------------------------------------------------ Prog ID: B129 PI: Shelton, Robin Institution: Johns Hopkins University Title: O VI Emission from the Interstellar Medium Currently there is no significant observation of the O VI flux from the Local Bubble. Such an observation will be very important for understanding the conditions and history of the Local Bubble and similar bubbles in the local interstellar medium. In this proposal, we describe a strategy for observing the Local Bubble, screening out other sources of flux, and minimizing the necessary spacecraft time spent on the guest observer investigation. The observed O VI flux will be combined with the soft X-ray spectrum for this direction in order to create the high energy spectral signature of the Local Bubble. The results will be compared with the average Local Bubble O VI column density in order to estimate the physical parameters of the hot gas. They will also be used to test and highly constrain theories for the formation and evolution of the Local Bubble and to determine the gas phase abundance of oxygen in hot gas. In addition, this observation will make it possible to determine the O VI flux from the halo. The combined Local Bubble and halo flux has been measured for a direction several degrees from the proposed Local Bubble observation. By subtracting the Local Bubble flux, the halo flux will be determined. ------------------------------------------------------------------------------ Prog ID: B130 PI: Heap, Sara R. Institution: NASA's Goddard Space Flight Center Title: Solar Ultraviolet Radiation and the Origin of Life on Earth We are currently using STIS and EUVE to obtain high-quality, far-UV (1160--1700AA ) and extreme-UV (60--760AA ) observations of three analogs of the early Sun. We now propose to obtain FUSE spectra of these three stars in order to obtain spectral coverage over the wavelength range, 60 -- 1700 AA. We will perform a detailed non-LTE analysis of each star, which involves constructing a model photosphere and an empirical model chromosphere that can be used to extrapolate the emission to the Lyman continuum region. Given a realistic flux distribution of the early Sun by proxy, we will then develop photochemical models of weakly reducing primitive atmospheres to determine the lifetime and photochemistry of methane (CH_4). In particular, we will estimate the concentration of CH_4 in the prebiotic atmosphere (sim 3.5 b.y. ago) and during the Late Archean 2.5-3.0 b.y. ago). We will use these results to determine whether methane would have been sufficiently abundant to help offset the reduced solar luminosity at that time. We will also use our photochemical models to solve for the concentrations of greenhouse gases and important pre-biotic molecules. ------------------------------------------------------------------------------ Prog ID: B131 PI: Keyes, Charles D. Institution: Space Telescope Science Institute Title: Outbursts in Symbiotic Binaries To study the accretion and outbursts in symbiotic systems, we have organized a multi-wavelength, target-of-opportunity (TOO) observing program including Chandra, XMM, HST, and the VLA. XMM observations have been approved and proposed Chandra data will provide supporting high-resolution spectral coverage that will probe the hottest regions during an outburst. XMM TOO observations have been approved for any of the targets on our list that go into outburst between July 2000 and at least December 2001 the XMM A01). The XMM observations will provide UV and soft X-ray coverage at several times during an outburst. The evolution of the X-ray and UV spectrum throughout the outburst will play a vital role in distinguishing between the outburst models currently in contention for describing the behavior of these outbursts. Emission line strengths of the FUSE-band species, especially when combined with lines of the same species from the other spectral regions, will provide diagnostics of the colliding windshock region. The high-resolution of FUSE-band absorption features will provide a unique opportunity to probe several aspects of the outburst material. Note especially that FUSE provides important information for the analysis of the x-ray data as FUSE observations of HI absorption are at sufficiently high resolution to allow the separation of the interstellar component from the systemic component of the absorption. ------------------------------------------------------------------------------ Prog ID: B134 PI: Heap, Sara R. Institution: NASAs Goddard Space Flight Center Title: Towards Understanding Starburst Galaxies at Low and High Redshift We propose FUSE observations of a small set of OB stars in the SMC to supplement the extensive sample being taken by the FUSE PI team. The combined dataset will complete the coverage of representative OB stars at low metallicity. We will then combine the resulting FUSE spectral atlas with our existing HST spectral atlas of the same stars to form a comprehensive UV spectral library (900 - 1700 AA) of massive stars in the SMC. We will use this library itemto determine the stellar content (e.g. metallicity, star-formation rate) of star-forming galaxies at high redshift; itemto determine the properties, particularly mass-loss rates and abundances, of massive stars at low metallicities. ------------------------------------------------------------------------------ Prog ID: B137 PI: Kaiser, Mary Elizabeth Institution: The Johns Hopkins University Title: Intrinsic Absorption in the Seyfert 1 Galaxy NGC4593 Contemporaneous FUSE, XMM, and HST Observations High resolution HST spectra indicate that more than 50 Seyfert,1 galaxies possess an intrinsic UV absorber (Crenshaw et,al.,1999). Furthermore, there appears to exist a one-to-one correspondence between the presence of the warm X-ray absorber and intrinsic absorption in the UV. However, the UV absorption often arises in multiple components some of which may be lower column density and lower ionization. The far-UV bandpass of FUSE provides a critical tool for understanding the nature and origin of this gas. The high spectral resolution of FUSE permits the isolation of multiple kinematic components in the absorption spectrum of O,VI facilitating the association of an UV absorber with its X-ray counterpart. Furthermore, O,VI is critical for establishing the connection between the lower ionization lines of C,IV and N,V seen in the UV with the high ionization absorption edges of O,VII and O,VIII seen in the X-ray. We propose to examine the near-nuclear gaseous environment of NGC,4593 by obtaining near-simultaneous observations of this target in the UV (HSTSTIS), far-UV (FUSE) and X-ray (XMM). We have been granted time with both HSTSTIS and XMM for contemporaneous observation of this target. The addition of contemporaneous FUSE observations of O,VI will greatly enhance our understanding of the ionization and kinematic state of the gas in the near-nuclear environment of this Seyfert,1 galaxy and provide a rare opportunity to probe the ionization state of the gas over a wide range of ionization levels. ------------------------------------------------------------------------------