# Summary of K2 Program GO7065

Title: Monitoring the Closest Stars in K2 Fields 6 and 7

PI: Jao, Wei-Chun (Georgia State University)
CoIs: Henry, Todd J.

The fundamentals of stellar astronomy are built upon studies of nearby stars. Because of their proximity and brightness, they provide us the most reliable answers to questions about stellar populations, multiplicity, structure, and evolution. In addition, a detailed understanding of their physical properties (temperatures, radii, masses, etc.) is essential to the effects that stellar hosts have on any exoplanets orbiting them. The RECONS group (www.recons.org) is dedicated to the study of nearby stars. Since 1994, we have discovered and characterized nearby red, brown, and white dwarfs, (Jao et al. 2005, 2014; Henry et al. 2006; Subasavage et al. 2009; Riedel et al. 2014). The team is currently constructing the RECONS 25 Parsec Database, which at present includes more than 3000 stars, brown dwarfs, and exoplanets with parallaxes greater than 40 mas and errors less than 10 mas. 

Much of the motivation of the K2 mission is to identify potentially habitable planets transiting stars that are close enough for detailed follow-up. Many nearby stars have been targeted for radial velocity (e.g., Chubak et al. 2012), transiting (e.g., Berta et al. 2013), and high-resolution imaging surveys (e.g., Horch et al 2012) to find close companions or planets. We propose to utilize the temporal monitoring in K2 fields 6 and 7 to observe the 6 nearest systems (including 7 components) with trigonometric parallaxes placing them closer than 25 pc. These stars are K5  M4 dwarfs and a white dwarf, a sample which covers the most abundant populations of our Galaxy. Of particular interest is the GJ0729 (M3.5V), which is the 9th closest star in our solar neighborhood.

Keplers long and short cadence data will allow us to search for transiting exoplanets around these nearby stars, none of which have yet been found to harbor planets.  To date, there are 978 confirmed planets discovered by Kepler, yet the closest planet, Kep-3b, is at 33 pc. Most of the systems either do not have parallaxes or are farther than 100 pc.  Although the odds of detecting a transit among only 7 targets is small, the variability data are valuable for astrophysical studies of the nearest stars and an investment in the future, should non-transiting planets eventually be discovered around these stars.  Month-long monitoring of the M dwarfs in particular can provide context for continuing RECONS work on M dwarf variability over timescales of 3-12 years, sampled at observing cadences of a few times/year (Jao et al. 2011; Hosey et al. 2014, accepted). In these studies we find that only 10% of M dwarfs vary by more than 20 mmag at optical wavelengths, implying that most M dwarfs are suitable for stable planetary environments.  These two campaigns are both in the south and can be observed at the CTIO/SMARTS 0.9m, where the RECONS variability data are taken.  Thus, we can set-up a complementary long-term variability monitoring program in conjunction to Keplers short-term data and will gather a full picture of the stars variability and flaring events, which are important to habitability of planets. We note that this proposal is similar to the one we submit for field 4 and 5 to observe 21 stars, which is currently under review.

# Targets requested by this program that have been observed (3)
EPIC ID, RA (J2000) [deg], Dec (J2000) [deg], magnitude, Investigation IDs
213817346, 291.9700928, -28.1879711, 13.335, GO7002_LC|GO7060_LC|GO7065_LC|GO7046_LC
214269391, 282.5881653, -26.9236298, 9.349, GO7008_LC|GO7060_LC|GO7065_LC|GO7046_LC
215632069, 282.4556885, -23.8362293, 9.293, GO7008_LC|GO7041_LC|GO7065_LC|GO7057_LC|GO7016_LC|GO7005_LC|GO7046_LC|GO7023_LC