Nicole Allard

Astronome

Institut d'astrophysique de Paris

98 bis Boulevard Arago

75014 Paris

Téléphone : +33 (1) 45 43 35 74

Email

Liste des Publications - Tables

Equipe : Physique stellaire, Physique des étoiles chaudes et variables

Travaux :

Etude théorique des profils de raies atomiques perturbées par collisions.

Applications

Etoiles particulières de Population I de type lamboo
Etoiles vieilles de la Branche Horizontale
Naines blanches de type spectral DA dont l'atmosphère est constituée d'hydrogène pur.
Naines brunes et planètes géantes.

Research interest

Theory of spectral line profiles, with emphasis on neutral perturbers, mainly in all problems related to satellite line formation.
Collaboration since many years with John Kielkopf (U.S.A.) to the interpretation of laboratory data.
These calculations are of great theoretical interest in atomic physics, but have also important applications in astronomy.

1- The fruitful convergence of several lines of research has allowed us to explain unexpected features in the ultraviolet spectra
of DA White Dwarfs and peculiar A stars (metal-deficient A stars : Lamboo stars, metal-poor horizontal branch stars).
This has led to several collaborations with astronomers, and the involvement in optical (ESO)
as well as space-based (IUE, HST, FUSE) observations.
Theoretical calculation of Lyman alpha, Lyman beta, Lyman gamma and Balmer alpha line profiles perturbed
by neutral hydrogen and protons have been done in a large range of temperatures.

T-dependent tables have been built to be implemented into TLUSTY and SYNSPEC, the atmosphere model
and synthetic spectra codes of I. Hubeny and T. Lanz.

2- Absorption profiles of alkali perturbed by high densities of helium and molecular hydrogen for the construction
of models atmospheres and synthetic spectra for cool Brown Dwarfs and Extrasolar Giant Planets.

T-dependent tables have been built to be implemented into PHOENIX



Dernières modifications : 28/11/2005