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±0.12R⊕ sub-Neptune in a 9.5 day orbit, and a 4.31−0.27+0.24R⊕ 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.
@article{arxiv.1701.03807,
title = {A Multi-Planet System Transiting the $V$ = 9 Rapidly Rotating F-Star HD 106315},
author = {Joseph E. Rodriguez and George Zhou and Andrew Vanderburg and Jason D. Eastman and Laura Kreidberg and Phillip A. Cargile and Allyson Bieryla and David W. Latham and Jonathan Irwin and Andrew W. Mayo and Michael L. Calkins and Gilbert A. Esquerdo and Jessica Mink},
journal= {arXiv preprint arXiv:1701.03807},
year = {2017}
}