Artist views of the evaporating extrasolar planet HD209458b
Crédits:
European Space Agency, Alfred Vidal-Madjar (Institut d'Astrophysique de Paris, CNRS, France) and NASA GIF (0.5 Mo)
GIF (0.5 Mo)
TIF (2.5 Mo)
TIF (2.5 Mo)
Artist views of the evaporating extrasolar planet HD209458b
Crédits: Jérémie Vidal-Madjar (http://lembo.free.fr)
This artistic view represents the detection :
The UV stellar flux at Lyman-alpha is absorbed by the evaporating hydrogen in the upper atmosphere
(black cloud in front of the star HD209458).
A computer simulation of the evaporating extra-solar planet HD209458b. Download MPEG (13 Mo),
GIF (1 Mo), GIF (9 Mo), AVI (3 Mo)
This simulation shows the hydrogen atoms strewn out into
a comet-like tail (blue points).
The graphic shows the 9 measurements of lyman alpha flux during the transit of the planet (blue squares).
The green line is the simulation.
A computer simulation of the evaporating extra-solar planet HD209458b. Download MPEG (13 Mo),
Gif (6 Mo),
Gif (1 Mo),
AVI (3 Mo)
This simulation shows the hydrogen atoms strewn out into
a comet-like tail (blue points).
The right-bottom panel shows the absorption spectrum
due to the evaporating hydrogen when the planet is passing in front of
its star.
The Lyman alpha line of the star HD209458, as observed with the Hubble Space Telescope.
The green line shows the stellar flux as a function of the wavelength, as it
is observed when the planet is not in front of the star.
When the planet transits in front of HD209458, the flux is fainter by about 15% (red line)
in particular at wavelengths between 1215 and 1215.5 Angstroms.
This shows that an hydrogen cloud which is about 15% the size of the star, is
flowing away at 100 kilometers per second.
The Lyman alpha flux of the star HD209458 as a function of the time.
This plot shows the 9 measurements of the Lyman alpha flux obtained
with the Hubble Space Telescope before and during the transit of the
planet in front of its star.
When the planet is in front of its star, this
last one is less bright by about 15%.
This is the signature of an
extended atmosphere of hydrogen.
