We propose to constrain the sky-projected obliquity of the hot Jupiter WASP-158b by observing its Rossiter-McLaughlin during transit with Gemini-N/MAROON-X. WASP-158b is a rare hot Jupiter we can rule out the inward migration due to gravitational perturbations by stellar or planetary companions (high eccentricity migration; HEM). As HEM is the only mechanism known to excite significant obliquity, any obliquity we observe in the “non-HEM" WASP-158b is likely attained in the protoplanetary disk phase. The empirical correlation of stellar mass with obliquity strongly suggests an oblique orbit for WASP-158b, whose host is a relatively massive F-type star. The observation of non-HEMs like WASP-158b is crucial, as the recent discoveries of misaligned protoplanetary disks challenge our preconception that hot Jupiters or planets in general form in “aligned" protoplanetary disks with zero obliquity (primordial alignment). Furthermore, it is still unclear how often disk obliquity is retained in planets, as some studies show that disk obliquity can be damped during planet formation. The addition of WASP-158b, whether aligned or misaligned, is therefore essential to the the still sparse (N<10) obliquity sample of non-HEMs to better bridge the theories of disk and planet formation.
This document was translated from LATEX by HEVEA.