Searching for volcanic activity and a mercury-like exosphere of the super-Earth HD3167 b

Abstract

ABSTRACT HD3167 b 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 HD3167 b 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 Ultraviolet and Visual Échelle Spectrograph in order to search for presence of lines originating from the exosphere of the planet such as the $\rm Na\, D_{1,2}$ and Ca ii H&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 $I_{p,\lambda }/I_{*,\lambda }=1.5\, 10^{-3}$ for the Ca ii 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 $\rm NaD_{1,2}$ 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. we took the text from the GAIA, SIMBAD and APPLAUSE web-pages.