# Summary of K2 Program GO13009 Title: Planet Formation and Fundamental Stellar Parameters at the Early Stages of Stellar Evolution PI: Rizzuto, Aaron C (University of Texas at Austin) CoIs: Muirhead, Philip Steven; Jensen, Eric L; Kraus, Adam L; Covey, Kevin; Ireland, Michael James; Mann, Andrew Withycombe The Taurus-Auriga star-forming complex of dark clouds and the surrounding young stars are a benchmark pre-main sequence population for studying detailed star and planet formation in a largely isolated environment. The entire Taurus complex consists of more than 400 comoving members with ages of 0-3 Myr, with ~75% of the solar-type members hosting a gaseous primordial circumstellar disk. Taurus is one of the nearest northern star-forming regions (d=145 pc) and has a relatively low stellar density even in the centers of filaments (<10 per cubic parsec, e.g. Kraus & Hillenbrand 2009). K2 campaign 13 will directly target a large fraction of the Taurus region, making campaign 13 the richest campaign in terms of newly formed stars around which to search for planets. The K2 mission is ideal for measuring planet formation timescales and migration pathways. Over the past 10 campaigns, multiple groups of young stars have been observed by K2, ranging from the 10 Myr old Upper Scorpius OB association, through the ~120 Myr old Pleiades, and the ~600 Myr old Hyades moving group. The detected, and soon to be detected exoplanets in these samples of different age will reveal the evolution of the exoplanet population in the early stages of stellar life. The 0-3 Myr old Taurus star-forming region will be a critical youngest-age sample in the forming picture of exoplanet population evolution. The detection, or absence of transiting exoplanets at the age of Taurus will place strong constraints of the timescales of exoplanet formation and migration. We propose to use K2 in campaign 13, in long-cadence mode, to search confirmed and probable Taurus members for the youngest known transiting exoplanets. We have already developed tools, which we have applied to existing data, to extract lightcurves from K2 data and remove instrumental systematics. We have also developed methods for removing stellar activity signals from the lightcurves of young stars, and have identified candidate transiting exoplanets in the K2 Upper Scorpius data from campaign 2. We will extend these techniques for analysis of the Taurus data taken in campaign 13. We have planned a robust follow-up campaign for any detected Taurus planets, utilizing a full suite of techniques including multi-band ground based photometry to confirm the planetary nature of the transits, and high-resolution imaging and IR spectroscopy to detect stellar companions. We also expect to discover ~5 eclipsing binary systems in the proposed sample, which, with ground based follow-up, will offer revolutionary constraints at the youngest reaches of the pre-main sequence evolutionary models. We are already following up 10 eclipsing binaries in Upper Scorpius from K2 campaign 2, and a further 20 in older nearby clusters. We will add any new eclipsing binaries in Taurus to this program. We have built a complete census of confirmed Taurus members from all of the existing literature and our own spectroscopic confirmation, and have supplemented this with a kinematic search for high confidence candidate new members (following the method of Rizzuto et al. 2011,2015). In total, we propose to observe 445 targets with 9