Global 3D hydrodynamic modeling of absorption in Ly{\alpha} and He 10830 A lines at transits of GJ3470b

TL;DR

This paper presents a 3D hydrodynamic model of GJ3470b's atmosphere to explain observed absorption in Lyα and He 10830 lines, revealing interactions with stellar wind and constraining atmospheric composition.

Contribution

It introduces a comprehensive 3D hydrodynamic simulation of exoplanet atmospheric absorption in Lyα and He 10830 lines, linking observations to stellar wind interactions.

Findings

Absorption in Lyα and He lines results from planetary atmosphere and stellar wind interaction.

Model constrains stellar plasma parameters and helium abundance in the atmosphere.

Simulation matches observed absorption features in transit data.

Abstract

Warm Neptune GJ3470b has been recently observed in 23S-23P transition of metastable helium, yielding absorption of about 1% in Doppler velocity range of [-40; 10] km/s. Along with previous detection of absorption in Ly{\alpha} with depth of 20-40% in the blue and red wings of the line, it offers a complex target for simulation and testing of the current models. Obtained results suggest that absorption in both these lines comes from interaction of expanding upper planetary atmosphere with stellar plasma wind, allowing to constrain the stellar plasma parameters and the helium abundance in planet atmosphere.