Evaporation of the planet HD 189733b observed in H I Lyman-α
By A. L. D. Etangs, David Ehrenreich, A. Vidal-Madjar, Gilda E. Ballester, J. D'esert, R. Ferlet, G. Hébrard, D. Sing, K.-O. Tchakoumegni, S. Udry. 2010
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We observed three transits of the extrasolar planet HD 189733b in HI Lyman-α and in a few other lines in the ultraviolet with HST/ACS, in the search for atmospheric signatures. We detect a transit signature in the Lyman-α light curve with a transit depth of 5.05 ± 0.75%. This depth exceeds the occultation depth produced by the planetary disk alone at the 3.5σ level (statistical). Other stellar emission lines are less bright, and, taken individually, they do not show the transit signature, while the whole spectra redward of the Lyman-α line has enough photons to show a transit signature consistent with the absorption by the planetary disk alone. The transit depth's upper limits in the emission lines are 11.1% for OI λ1305 A and 5.5% for CII λ1335 A lines. The presence of an extended exosphere of atomic hydrogen around HD 189733b producing 5% absorption of the full unresolved Lyman-α line flux shows that the planet is losing gas. The Lyman-α light curve is well-fitted by a numerical simulation of escaping hydrogen in which the planetary atoms are pushed by the stellar radiation pressure. We constrain the escape rate of atomic hydrogen to be between 10 9 and 10" g s -1 and the ionizing extreme UV flux between 2 and 40 times the solar value (1-σ), with higher escape rates corresponding to larger EUV flux. The best fit is obtained for dM/dt = 10 10 g s -1 and an EUV flux F EUV = 20 times the solar value. HD 189733b is the second extrasolar planet for which atmospheric evaporation has been detected.
Subfields: Astronomy and Astrophysics, Instrumentation
View Paper: https://www.semanticscholar.org/paper/6b5f39f6724941d848a1dfc43aabd4dbfe9dcb78
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Citations in the corpus
- The Hubble Space Telescope PanCET Program: Exospheric Mg ii and Fe ii in the Near-ultraviolet Transmission Spectrum of WASP-121b Using Jitter Decorrelation (2019, background): “Detections of H i and O i have also been made in HD 189733b (Lecavelier Des Etangs et al. 2010; Lecavelier des Etangs et al. 2012; Ben-Jaffel & Ballester 2013).”
- Extremely Irradiated Hot Jupiters: Non-oxide Inversions, H− Opacity, and Thermal Dissociation of Molecules (2018, background): “The Upper Atmosphere and Atmospheric Escape on Hot Jupiters Atmospheric escape has been observed on a handful of hot Jupiters to date, namely HD209458b, HD189733b, and WASP-12b (Vidal-Madjar et al. 2003; Lecavelier des Etangs et al. 2010, 2012; Fossati et al. 2010).”
- A New Window into Escaping Exoplanet Atmospheres: 10830 Å Line of Helium (2017, background): “Observational evidence for atmospheric escape has been obtained for a handful of exoplanets to date in the form of a strong absorption signal detected in the wings of the hydrogen Lyα line, but also in some UV lines of metals (Vidal-Madjar et al. 2003, 2004; Lecavelier Des Etangs et al. 2010; Linsky”
- ROTATION AND WINDS OF EXOPLANET HD 189733 b MEASURED WITH HIGH-DISPERSION TRANSMISSION SPECTROSCOPY (2015, background): “This richness of information translates into observational evidence for rather unique features, such as atmospheric escape (Lecavelier Des Etangs et al. 2010; Jensen et al. 2012) and the prominence of haze (Pont et al. 2008; Sing et al. 2011) masking most of the spectral features in the optical tran”