Global 3D hydrodynamic modeling of in-transit Lyα absorption of GJ436b

Abstract

Using a global 3D, fully self-consistent, multi-fluid hydrodynamic model, we simulate the escaping upper atmosphere of the warm Neptune GJ436b, driven by the stellar XUV radiation impact and gravitational forces and interacting with the stellar wind. Under the typical parameters of XUV flux and stellar wind plasma expected for GJ436, we calculate in-transit absorption in Lyα and find that it is produced mostly by Energetic Neutral Atoms outside of the planetary Roche lobe, due to the resonant thermal line broadening. At the same time, the influence of radiation pressure has been shown to be insignificant. The modelled absorption is in good agreement with the observations and reveals such features as strong asymmetry between blue and red wings of the absorbed Lyα line profile, deep transit depth in the high velocity blue part of the line reaching more than 70%, and the timing of early ingress. On the other hand, the model produces significantly deeper and longer egress than in observations, indicating that there might be other processes and factors, still not accounted, that affect the interaction between the planetary escaping material and the stellar wind. At the same time, it is possible that the observational data, collected in different measurement campaigns, are affected by strong variations of the stellar wind parameters between the visits, and therefore, they cannot be reproduced altogether with the single set of model parameters.

34 pages and 18 figures

References in corpus (17)

• A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b
• Lyman-$\alpha$ Transit Spectroscopy and the Neutral Hydrogen Tail of the Hot Neptune GJ436b
• Energetic neutral atoms as the explanation for the high velocity hydrogen around HD 209458b
• Magnetic moment and plasma environment of HD 209458b as determined from Ly$\alpha$ observations
• Classification of magnetized star--planet interactions: bow shocks, tails, and inspiraling flows
• Exoplanet HD209458b: inflated hydrogen atmosphere but no sign of evaporation
• Magnetically controlled mass loss from extrasolar planets in close orbits
• The long egress of GJ~436b's giant exosphere
• Atmosphere Expansion and Mass Loss of Close-Orbit Giant Exoplanets heated by Stellar XUV. II. Effects of Planetary Magnetic Field, Structuring of inner Magnetosphere
• Magnetohydrodynamic Simulations of Hot Jupiter Upper Atmospheres
• Atmosphere expansion and mass loss of close-orbit giant exoplanets heated by stellar XUV: I. Modeling of hydrodynamic escape of upper atmospheric material
• Two regimes of interaction of a Hot Jupiter's escaping atmosphere with the stellar wind and generation of energized atomic hydrogen corona
• Lyα Absorption at Transits of HD 209458b: A Comparative Study of Various Mechanisms Under Different Conditions
• Ultraviolet C II and Si III Transit Spectroscopy and Modeling of the Evaporating Atmosphere of GJ436b
• Effect of stellar wind induced magnetic fields on planetary obstacles of non-magnetized hot Jupiters
• The Influence of Coronal Mass Ejections on the Gas Dynamics of the Atmosphere of a "Hot~Jupiter" Exoplanet
• Transit Ly-$\alpha$ signatures of terrestrial planets in the habitable zones of M dwarfs

Cited by in corpus (3)

• GJ 436b and the stellar wind interaction: simulations constraints using Ly$\alpha$ and H$\alpha$ transits
• Three-dimensional hydrodynamic simulations of the upper atmosphere of $\pi$ Men c: comparison with Ly$\alpha$ transit observations
• Simulation of 10830 Å absorption with a 3D hydrodynamic model reveals the solar He abundance in upper atmosphere of WASP-107b