Details

Autor(en) / Beteiligte

• Palle, E.
• Nortmann, L.
• Casasayas-Barris, N.
• Lampón, M.
• López-Puertas, M.
• Caballero, J. A.
• Sanz-Forcada, J.
• Lara, L. M.
• Nagel, E.
• Yan, F.
• Alonso-Floriano, F. J.
• Amado, P. J.
• Chen, G.
• Cifuentes, C.
• Cortés-Contreras, M.
• Czesla, S.
• Molaverdikhani, K.
• Montes, D.
• Passegger, V. M.
• Quirrenbach, A.
• Reiners, A.
• Ribas, I.
• Sánchez-López, A.
• Schweitzer, A.
• Stangret, M.
• Zapatero Osorio, M. R.
• Zechmeister, M.

Titel

A He I upper atmosphere around the warm Neptune GJ 3470 b

Ist Teil von

• Astronomy and astrophysics (Berlin), 2020-06, Vol.638, p.A61

Ort / Verlag

Heidelberg: EDP Sciences

Erscheinungsjahr

2020

Quelle

EZB-FREE-00999 freely available EZB journals

Beschreibungen/Notizen

• High resolution transit spectroscopy has proven to be a reliable technique for the characterization of the chemical composition of exoplanet atmospheres. Taking advantage of the broad spectral coverage of the CARMENES spectrograph, we initiated a survey aimed at characterizing a broad range of planetary systems. Here, we report our observations of three transits of GJ 3470 b with CARMENES in search of He (2 3 S) absorption. On one of the nights, the He  I region was heavily contaminated by OH − telluric emission and, thus, it was not useful for our purposes. The remaining two nights had a very different signal-to-noise ratio (S/N) due to weather. They both indicate the presence of He (2 3 S) absorption in the transmission spectrum of GJ 3470 b, although a statistically valid detection can only be claimed for the night with higher S/N. For that night, we retrieved a 1.5 ± 0.3% absorption depth, translating into a R p ( λ )∕ R p = 1.15 ± 0.14 at this wavelength. Spectro-photometric light curves for this same night also indicate the presence of extra absorption during the planetary transit with a consistent absorption depth. The He (2 3 S) absorption is modeled in detail using a radiative transfer code, and the results of our modeling efforts are compared to the observations. We find that the mass-loss rate, Ṁ , is confined to a range of 3 × 10 10 g s −1 for T = 6000 K to 10 × 10 10 g s −1 for T = 9000 K. We discuss the physical mechanisms and implications of the He  I detection in GJ 3470 b and put it in context as compared to similar detections and non-detections in other Neptune-size planets. We also present improved stellar and planetary parameter determinations based on our visible and near-infrared observations.