Volcanic activity and the exosphere of HD3167b

TL;DR

This study investigates the potential volcanic activity and exosphere of the super-Earth HD3167b by calculating electromagnetic induction heating and searching for spectral lines indicative of volcanic gases, providing constraints on atmospheric signatures.

Contribution

It combines theoretical electromagnetic induction heating calculations with observational UVES data to search for volcanic and exospheric signatures on HD3167b, a novel approach for such exoplanets.

Findings

Electromagnetic induction heating can be significant for some magnetic field strengths.

No definitive spectral lines from volcanic activity were detected, setting upper limits.

Results suggest volcanic activity and exosphere signatures may be variable or absent at times.

Abstract

HD3167b is a transiting super-Earth that has a density which is consistent with a rocky composition. The planet is exposed to strong radiation, intense stellar wind, and likely strong tidal forces and induction heating. According to theory, planets that are so close to the star should have an atmosphere like Mercury but much more extended and denser. Other theories predict that such planets have a lava lake on their surfaces and exhibit an enormous volcanic activity. We have calculated the heating by electromagnetic induction to estimate if it can drive significant volcanic activity at HD3167b and shown that for some magnetic fields the heating can be substantial. HD3167 is an ideal target to search for the exosphere of a planet, and signs of volcanic activity. We observed the planet in-and out-of transit with UVES in order to search for presence of lines originating from the exosphere of the planet such as the NaD1,2 and CaIIH&K lines as well as numerous [S II],[S III], and [O III] lines that are tracers of volcanic activity. We derived upper limits for the ratios of the line fluxes to the stellar flux. The upper limits that we derived are Ip,lambda/I*,lambda=1.5 10-3 for the CaII,H&K lines, and I_p,lambda/I*,lambda=7.2 10-4 and I_p,lambda/I_*,lambda=3.3 10-4 for the NaD_1,2 lines, respectively. The fact that our upper limits correspond to previous detections in 55 Cnc e shows that not all super-Earth show these lines all the time and that they might be variable.