Highlight: Evaporation of the planet HD189733b observed in HI Lyman-alpha (vol. 514)

Vol. 514In section 10. Planets and planetary systems21 May 2010

Evaporation of the planet HD 189733b observed in HI Lyman-alpha

by A. Lecavelier des Etangs, D. Ehrenreich, A. Vidal-Madjar, et al., A&A 514, A72

Ever since the discovery of 51 Peg b, close-in exoplanets have been predicted to slowly evaporate, but the measurement of this evaporation for HD 209458b in 2003 came as a surprise. Here, Lecavelier et al. use HST/ACS observations in Lyman-alpha (1215 Angström) to provide new evidence of evaporation in another famous exoplanet: HD 189733b, a 1.13 Jupiter mass exoplanet in a 2.21 day orbital period. The inferred evaporation rate, around 10^10 g/s, is consistent with that of HD209458b. However, the measurements might be affected by systematics and would have to be confirmed, for example with the repaired STIS spectrograph onboard HST.