ON THE EXISTENCE OF ENERGETIC ATOMS IN THE UPPER ATMOSPHERE OF EXOPLANET HD209458b

摘要: Stellar irradiation and particle forcing strongly affect the immediate environment of extrasolar giant planets orbiting near their parent stars. However, it is not clear how energy deposited over planetary atmosphere, nor momentum spaces different species that populate system are modified. Here, we use far-ultraviolet emission spectra from HD209458 in wavelength range (1180-1710) A to bring new insight composition energetic processes play gas nebula around transiting companion. In frame, consider up-to-date atmospheric models exoplanet where implement non-thermal line broadening simulate impact on transit absorption superthermal atoms (H I, O C II) populating upper layers nebula. Our sensitivity study shows for all existing models, a significant required I probably II lines order fit observed absorptions. show preferentially heated compared background with effective temperatures as large T /TB ~ 10 5 II. By contrast, situation much less H because several could Lyα observations including either thermal an atmosphere has dayside vertical column [H I] 1.05 × 1021 cm–2, or extended but hot If stellar origin populations lost planet energized outer nebula, our finding most should converge toward one population I]hot (2-4) 1013 cm–2 temperature (1-1.3) 106 K, bulk velocity be rather slow.