1. Simulation of 10 830 Å absorption with a 3D hydrodynamic model reveals the solar He abundance in upper atmosphere of WASP-107b.
- Author
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Khodachenko, M L, Shaikhislamov, I F, Fossati, L, Lammer, H, Rumenskikh, M S, Berezutsky, A G, Miroshnichenko, I B, and Efimof, M A
- Subjects
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UPPER atmosphere , *RADIATION pressure , *ABSORPTION , *METASTABLE states , *ULTRAVIOLET radiation - 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. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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