Magnetic moment and plasma environment of HD 209458b as determined from Ly$\alpha$ observations

Abstract

Transit observations of HD 209458b in the stellar Lyman-$\alpha$ (Ly$\alpha$) line revealed strong absorption in both blue and red wings of the line interpreted as hydrogen atoms escaping from the planet's exosphere at high velocities. The following sources for the absorption were suggested: acceleration by the stellar radiation pressure, natural spectral line broadening, charge exchange with stellar wind. We reproduce the observation by means of modelling that includes all aforementioned processes. Our results support a stellar wind with a velocity of $\approx 400$ km$\times$s${}^{-1}$ at the time of the observation and a planetary magnetic moment of $\approx 1.6\times 10^{26}$ A$\times$m${}^2$.

arXiv commentThis is the author's version of the work. It is posted here by permission of the AAAS for non-commercial research use only. The definitive version was published in Science, vol. 346, p. 981, 21 November 2014, DOI: 10.1126/science.1257829. 3 pages, 3 figures

References in corpus (18)

• New Mass Loss Measurements from Astrospheric Lyman-alpha Absorption
• Observations of Mass Loss from the Transiting Exoplanet HD 209458b
• Homogeneous studies of transiting extrasolar planets. III. Additional planets and stellar models
• Stellar Lyman-alpha Emission Lines in the Hubble Space Telescope Archive: Intrinsic Line Fluxes and Absorption from the Heliosphere and Astrospheres
• Lyman-$\alpha$ Transit Spectroscopy and the Neutral Hydrogen Tail of the Hot Neptune GJ436b
• The escape of heavy atoms from the ionosphere of HD209458b. I. A photochemical-dynamical model of the thermosphere
• 3D model of hydrogen atmospheric escape from HD209458b and HD189733b: radiative blow-out and stellar wind interactions
• Energetic neutral atoms as the explanation for the high velocity hydrogen around HD 209458b
• A magnetic field evolution scenario for brown dwarfs and giant planets
• Exoplanet HD209458b: inflated hydrogen atmosphere but no sign of evaporation
• On the existence of energetic atoms in the upper atmosphere of exoplanet HD209458b
• Characterizing the thermosphere of HD209458b with UV transit observations
• Colliding Planetary and Stellar Winds: Charge Exchange and Transit Spectroscopy in Neutral Hydrogen
• The HARPS search for southern extra-solar planets. XXXI. Magnetic activity cycles in solar-type stars: statistics and impact on precise radial velocities
• Stellar wind interaction and pick-up ion escape of the Kepler-11 "super-Earths"
• XUV exposed, non-hydrostatic hydrogen-rich upper atmospheres of terrestrial planets II: Hydrogen coronae and ion escape
• On the sensitivity of extrasolar mass-loss rate ranges: HD 209458b a case study
• GMRT search for 150 MHz radio emission from the transiting extrasolar planets HD189733b and HD209458b

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