And the Oscar Goes to: BD+20 1790 for "The Mystery of the Unseen Companion"

Abstract

BD+20 1790 is a young, rich metal and very active late–type K5Ve star. Our group has been developing a study of stellar activity and kinematics for this star over the past years. Previous results show a high level of stellar activity, with the presence of prominence-like structures, spots on surface and strong flare events. Radial velocity (RV) variations with a semi-amplitude of up to 1km s⁻¹ were detected. When the nature of these variations was investigated it was found that they are not due to stellar activity. Based upon the analysis of bisector velocity span, as well as Ca II H & K emission, we report that the best explanation for RV variations is the presence of a sub–stellar companion. The Keplerian fit of the RV data yields an orbital solution for a close-in massive planet with an orbital period of 7.783days. Also, the presence of this close–in massive planet could be an interpretation for the high level of stellar activity detected.

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