Simulation of 10 830 Å absorption with a 3D hydrodynamic model reveals the solar He abundance in upper atmosphere of WASP-107b
Abstract
Transmission spectroscopy of WASP-107b revealed 7-8 per cent absorption at the position of metastable He I triplet at 10 830 Å in the velocity range of [-20; 10] km s-1. This absorption is stronger than that measured in other exoplanets. With a dedicated 3D self-consistent hydrodynamic multifluid model, we simulated the expanding upper atmosphere of WASP-107b and reproduced within the observations accuracy the measured He I absorption profiles, constraining the stellar X-ray and UV radiation (XUV) flux to 6-10 erg cm-2 s-1 at 1 au, and the upper atmosphere helium abundance He/H to 0.075-0.15. The radiation pressure acting on the metastable He I atoms was shown to be an important factor influencing the absorption profiles. Its effect is counterbalanced by the collisional depopulation of the He I metastable state. Altogether, the observed He I absorption in WASP-107b can be interpreted with the expected reasonable parameters of the stellar-planetary system and appropriate account of the electron and atom impact processes.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 2021
- DOI:
- 10.1093/mnrasl/slab015
- arXiv:
- arXiv:2101.12504
- Bibcode:
- 2021MNRAS.503L..23K
- Keywords:
-
- hydrodynamics;
- plasmas;
- planets and satellites: atmosphere;
- planets and satellites: individual: exoplanets;
- planets and satellites: physical evolution;
- planet-star interactions;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- to be published