A Multi-planet System Transiting the V = 9 Rapidly Rotating F-Star HD 106315
Vanderburg, Andrew; Cargile, Phillip A.; Bieryla, Allyson; Latham, David W.; Calkins, Michael L.; Esquerdo, Gilbert A.; Mayo, Andrew W.; Zhou, George; Kreidberg, Laura; Rodriguez, Joseph E.; Eastman, Jason D.; Irwin, Jonathan; Mink, Jessica
United States
Abstract
We report the discovery of a multi-planet system orbiting HD 106315, a rapidly rotating mid F-type star, using data from the K2 mission. HD 106315 hosts a 2.51 ± 0.12 R ⊕ sub-Neptune in a 9.5-day orbit and a {4.31}-0.27+0.24 {R}\oplus super-Neptune in a 21-day orbit. The projected rotational velocity of HD 106315 (12.9 km s-1) likely precludes precise measurements of the planets’ masses but could enable a measurement of the sky-projected spin-orbit obliquity for the outer planet via Doppler tomography. The eccentricities of both planets were constrained to be consistent with 0, following a global modeling of the system that includes a Gaia distance and dynamical arguments. The HD 106315 system is one of few multi-planet systems hosting a Neptune-sized planet for which orbital obliquity measurements are possible, making it an excellent test-case for formation mechanisms of warm-Neptunian systems. The brightness of the host star also makes HD 106315 c a candidate for future transmission spectroscopic follow-up studies.