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| Titel |
UV emissions of Hot Jupiters |
| VerfasserIn |
Hélène Ménager, Barthélemy Mathieu, Jean Lilensten  |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250039876
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| Zusammenfassung |
| In the solar system, the giant planets Jupiter and Saturn have bright aurorae due to particle
precipitation in the upper atmospheres. The brightest optical auroral emissions are emitted by
H and H2 in the UV and by H3+ in the IR.
Due to the short distance to the parent stars, hot Jupiters are likely to be bombarded by
intense stellar winds and UV fluxes and have strong emissions at the same wavelengths.
When detected, their UV emissions could bring helpful information to characterize the
upper atmospheres of the exoplanets. The first question to address is : are these emissions
bright enough to be observed from Earth and distinguished from the stellar UV emissions ?
We focus on Jupiter-like atmospheres, composed of H, H2 and He. Kinetic calculations allow
to estimate the electron flux throughout the atmosphere and to calculate excitation rates of the
upper levels of UV transitions of H and H2. Radiative transfer calculations are then done to
estimate the intensity of the emergent lines and the profile of the H Lyman alpha
line.
Using the Yelle (2004) atmosphere model for HD209458b, we evaluate the H Lyman
alpha dayglow of the planet. We also evaluate UV emissions of the planet caused
by the precipitation of particles with and without an intrinsec magnetic field. We
find that the Lyman alpha emission of the planet could reach 1/1000 of that of the
star.
It has been shown that the profile of the H Lyman alpha line is very sensitive to the
atmospheric model and to the energy of the precipitating electrons (Menager et al. 2010). We
see here a way to constrain the upper atmosphere of exoplanets and their particle
environment, that could be used by future UV telescopes.
References
R. Yelle, Aeronomy of extra-solar giant planets at small orbital distances, Icarus, volume
170, 2004
H. Menager, M. Barthélemy, and J. Lilensten, H Lyman alpha line in Jovian aurorae :
electron transport and radiative transfer coupled modelling, Astronomy & Astrophysics,
accepted |
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