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Alain Lecavelier des Etangs Institut d’Astrophysique de Paris

Spectroscopy of extrasolar planets atmosphere. Alain Lecavelier des Etangs Institut d’Astrophysique de Paris. Alfred Vidal-Madjar Jean-Michel Désert Roger Ferlet Guillaume Hébrard (IAP, Paris). Alain Lecavelier des Etangs Institut d’Astrophysique de Paris.

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Alain Lecavelier des Etangs Institut d’Astrophysique de Paris

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  1. Spectroscopy of extrasolar planets atmosphere Alain Lecavelier des Etangs Institut d’Astrophysique de Paris

  2. Alfred Vidal-MadjarJean-Michel DésertRoger FerletGuillaume Hébrard(IAP, Paris) Alain Lecavelier des Etangs Institut d’Astrophysique de Paris VLST Workshop STScI Feb. 26-27, 2004

  3. Spectroscopy of extrasolar planets atmosphere • Future is difficult to predict • In 1994, “When will the first extrasolar planet detected ? ” answers: 2000, 2010… • 1 year ago: detection of OI: “not within the current capabilities” • Prediction: Future is impossible to predict VLST Workshop STScI Feb. 26-27, 2004

  4. Spectroscopy of extrasolar planets atmosphere • What has been done (HST): (description of the present)4 UV detections of the bottom and upper atmosphere of HD 209458bin space, in the UV-optical wavelength range. • With a VLST: (extrapolation to the future from the present) • Large sample of extrasolar planets • Detailed view of planets around nearby stars • Toward Earth and Ocean-like planets VLST Workshop STScI Feb. 26-27, 2004

  5. Transits: a powerful and sensitive method VLST Workshop STScI Feb. 26-27, 2004

  6. Transit of HD 209458(Charbonneau et al. 2000) VLST Workshop STScI Feb. 26-27, 2004

  7. Radial velocity + Occultation depth HD 209458b (Mazeh et al. 2000) Period = 3.524738 days Mass = 0.69 ±0.05 MJupiter Radius = 1.35 ±0.04 RJupiter Density= 0.35 ±0.05 g/cm3

  8. ~0.01% accuracy

  9. HD 209458b: Detection of the atmosphere in NaI(Charbonneau et al. 2002) 0.0232 ± 0.0057 % VLST Workshop STScI Feb. 26-27, 2004

  10. Search for HI Lyman a(1216 Å) Y (slit aperture) 1214 1215 1216 1217 Wavelength (Å) VLST Workshop STScI Feb. 26-27, 2004

  11. VLST Workshop STScI Feb. 26-27, 2004

  12. 15 ±4% Flux Ratio Begin of transit End of transit Time (hours) VLST Workshop STScI Feb. 26-27, 2004

  13. -100 0 100 (km s-1) | | | Beforetransit Duringtransit Flux ratio 15 ±4% Time (hours) Wavelength (A) • HD209458b (1.35 RJupiter = 96,500 km)→ 1.6 % absorption • Roche Lobe (2.7 Rplanet = 3.6 RJupiter)→ 10 % absorption • Hydrogen: 15 % absorption → 3.2 Rplanet= 4.3 RJupiter= 300 000 km • →Beyond the Roche Lobe Hydrogen is escaping • Absorption width: –130 km/s to 100 km/s • Vesc = 54 km/s • →Beyond escape velocity Hydrogen is escaping • The planet is evaporating

  14. Escape rate estimateHow much for 15% absorption? VLST Workshop STScI Feb. 26-27, 2004

  15. Escape rate > 1010 g/s

  16. An extended upper atmospherearound the extrasolar planet HD209458b A. Vidal-Madjar (IAP) A. Lecavelier des Étangs (IAP) J.-M. Désert (IAP) G. E. Ballester (Univ. Arizona) R. Ferlet (IAP) G. Hébrard (IAP) M. Mayor (Obs. Genève) Nature 422, 143 (2003) VLST Workshop STScI Feb. 26-27, 2004

  17. HST G140L ObservationsOct-Nov 2003 • Fig 1 VLST Workshop STScI Feb. 26-27, 2004

  18. Terrestrial airglow Stellar spectrum SiIII H I Lyman a O I C II Stellar continuum VLST Workshop STScI Feb. 26-27, 2004

  19. Confirmation of the HI absorption HI Lyman a • Fig 2a Out of transit In transit Si III ~5 % Wavelength (Å) VLST Workshop STScI Feb. 26-27, 2004

  20. Vidal-Madjar et al. 2004 (astro-ph/0401457) Detection of Carbon and Oxygen Out of Transit C II In Transit O I ~13 % ±4.5 % ~8 % ±3.5 % Wavelength (Å) VLST Workshop STScI Feb. 26-27, 2004

  21. ConsequenceVidal-Madjar et al. (2004 astro-ph/0401457) • Oxygen and carbon are also present in the upper atmosphere of HD 209458b • They are carried out by the hydrogen flow: HYDRODYNAMICAL ESCAPE (« BLOW-OFF ») VLST Workshop STScI Feb. 26-27, 2004

  22. More can be done • Last observations must be confirmed (2.5s) • Other species are likely detectable with HST Cycle 13 proposal… VLST Workshop STScI Feb. 26-27, 2004

  23. Planets to be discovered Rad.Vel.< 2003 Harps2003 COROT (2006) KEPLER(2007/8) Today ~120 planets know 10m/s (present) 1m/s (2003 HARPS)

  24. A large number of targets for the VLST • ≥7% planet / star • 15% « Hot Jupiter » / planet  1% « Hot Jupiter » / star • 10% transiting planet / « Hot Jupiter »  0.1% transit / star • 10,000 G stars (V≤8)  10 « Hot Jupiter » transits on stars V≤8 • 85,000 G stars (V≤10)  85 transits on V≤10 • 300,000 G stars (V≤12)  300 transits on V≤12 VLST Workshop STScI Feb. 26-27, 2004

  25. Planets with Earth-like orbital distances For d=1AU, Probability Transit  R*/a=0.5% ~30% of known planets within 0.5-1.5 AU 0.15% 1AU-transiting planet per planetary system ~30 transiting planet on Earth-like orbit around a G-type star V≤12 (For giant planets only…) IF 25% low-mass planet/star ~30 transiting low-mass planet on Earth-like orbit around a G-type star V≤10 VLST Workshop STScI Feb. 26-27, 2004

  26. Summary of detection capabilities on V≤8 stars HST VLST Height species FUV 4% 0.4% 10,000 km H, C, O, CO, O2 NUV 1% 0.1% 2,500 km Fe, Mg, et al.; CO, NO Bands<0.1% <0.01% <250 km O3 Opt. 0.01% 0.001% 25 km Na, K, Li, OH (3090A) NUV-Opt Time scan VLST Workshop STScI Feb. 26-27, 2004

  27. Time-scan • HST observations used a total of ~100-200 minutes exposures during transits.  VLST gives diagnostics in few minutes exposure • Tingress=80 (Rp/RJup) (a/1AU) ½ minutesTHD209458= 22 minutes • Scan of the planets “weather” during the partial occultation phases (ingress, egress): VLST Workshop STScI Feb. 26-27, 2004

  28. Temperate Uranus(Ocean-planets)(A. Leger 2003) • Scale height: H = 250 (T/300K) (Rp/REarth)2 (Mp/MEarth)-1m km HO2 =8 km on the Earth • Uranus parameter (Rp=4REarth , Mp=15MEarth)  same scale height: HO2 =8 km Expected occultation depth ~0.001% …Likely detectable on broad-bands. VLST Workshop STScI Feb. 26-27, 2004

  29. Scientific goals • Structures of the atmosphere of extra-solar planets(composition, dust/clouds/haze content, “weather”). • Interaction between planets and stars • Evolution of planets atmosphere (escape, fate of remaining core..) • Probe of new kinds of planets (temperate Uranus, evaporation-modified hot-Jupiters) • Life ? (improve our knowledge of habitable planets) VLST Workshop STScI Feb. 26-27, 2004

  30. This picture shows also the Earth atmosphere with emission from hydrogen and oxygen at high (HST) altitude where the C/O is obviously very low. Terrestrial airglow Stellar spectrum SiIII H I Lyman a O I C II Stellar continuum VLST Workshop STScI Feb. 26-27, 2004

  31. END • END VLST Workshop STScI Feb. 26-27, 2004

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