Physical parameters of the upper atmosphere of the extrasolar planet HD209458b

Details Physical parameters of the upper atmosphere of the extrasolar planet HD209458b Physical parameters of the upper atmosphere of the extrasolar planet HD209458b

Jul 2004

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004hst..prop10145v&link_type=abstract

HST Proposal ID #10145

Physics

Hst Proposal Id #10145 Star Formation

Scientific paper

Every 3.5 days, the transits of the gaseous planet orbiting HD209458 offer the unique opportunity to investigate the spectral features of an extra-solar planetary atmosphere. Using HST, we first discovered the extended upper atmosphere of HD209458b through the detection of a 15% HI Lyman alpha absorption. We concluded that the hydrogen must be escaping the planet with a lower limit rate of 10^10 g/s {Vidal-Madjar et al. 2003}. Additional observations, subsequently allowed to detect OI and CII in the upper atmosphere implying that this atmosphere is hydrodynamically escaping {in "blow off", Vidal-Madjar et al. 2004}. Here we propose to further study this upper atmosphere to better constrain the "blow off" state by directly estimating the physical conditions and the flow characteristics. In particular we will determine the temperature and density at the base of the upper atmosphere {the thermosphere}, and the density distribution and ionization state just below that level. Comparison between the optical and ultraviolet occultation light curves will provide useful information on the molecular/haze content of the lower atmosphere. The observation of six HD209458b transits with HRC and SBC settings will allow the detection of many lines adressing these issues. The proposed observations will give us for the first time a detailed probe of the atmosphere of an "evaporating" extra-solar planet.With species as abundant as FeII or MgII, the damping wings in the strongest lines will start to form at levels around 1.9% absorption. Due to either the strength of the MgII doublet lines around 280 nm or the packing of FeII lines, strong absorptions arising from the accumulated damping wings should show up clearly in FeII and MgII. All these signatures should be easily detected even with the 40 to 100 Angstrom resolution of the PR200L prism in these spectral regions. In addition to these goals, any signature of molecules {e.g CO below 154 nm}, dust or haze should also show up as broad band absorption in both PR110L and PR200L settings. The estimate of the planet radius at different wavelengths in the UV would become possible for all efficient absorbers in this spectral range. The achievement of 0.1% precision in the occultation curves thus provides sensitivity high enough to potentially lead to important discoveries.

Affiliated with

Also associated with

No associations

Rating

Physical parameters of the upper atmosphere of the extrasolar planet HD209458b does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Physical parameters of the upper atmosphere of the extrasolar planet HD209458b, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Physical parameters of the upper atmosphere of the extrasolar planet HD209458b will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1011001