Details

Autor(en) / Beteiligte

• Allart, R
• Bourrier, V
• Lovis, C
• Ehrenreich, D
• Spake, J J
• Wyttenbach, A
• Pino, L
• Pepe, F
• Sing, D K
• Lecavelier des Etangs, A

Titel

Spectrally resolved helium absorption from the extended atmosphere of a warm Neptune-mass exoplanet

Ist Teil von

• Science (American Association for the Advancement of Science), 2018-12, Vol.362 (6421), p.1384-1387

Ort / Verlag

United States: The American Association for the Advancement of Science

Erscheinungsjahr

2018

Quelle

American Association for the Advancement of Science

Beschreibungen/Notizen

• Stellar heating causes atmospheres of close-in exoplanets to expand and escape. These extended atmospheres are difficult to observe because their main spectral signature-neutral hydrogen at ultraviolet wavelengths-is strongly absorbed by interstellar medium. We report the detection of the near-infrared triplet of neutral helium in the transiting warm Neptune-mass exoplanet HAT-P-11b using ground-based, high-resolution observations. The helium feature is repeatable over two independent transits, with an average absorption depth of 1.08 ± 0.05%. Interpreting absorption spectra with 3D simulations of the planet's upper atmosphere suggests it extends beyond 5 planetary radii, with a large scale height and a helium mass loss rate ≲ 3×10 g‧s A net blue-shift of the absorption might be explained by high-altitude winds flowing at 3 km‧s from day to night-side.