# Summary of K2 Program GO15041

Title: Rotation rates for stars in wide binary systems and a search for hierarchical triples in Kepler K2 campaigns 14-15-16.

PI: Lepine, Sebastien (Georgia State University)
CoIs: 

Wide binary systems are of high interest for both stellar astrophysics and exoplanet research. Because they were born and ejected from the same parent star cluster, they also share the same age and presumably have very similar chemical compositions. At the same time, their large separations mean that they essentially behave like single stars, and can also be observed and studied separately. For stellar astrophysics, these systems represent a unique means of testing stellar evolution models at moderate to old ages (2-12 Gy), complementing data available for younger ages from the study of nearby star clusters or young moving groups. In particular, old wide systems are critical to test the predictions of gyrochronology, which posit a relationship between the age of a low-mass star and its rotation rate, a relationship that may prove critical for dating exoplanet systems discovered by Kepler and other surveys. This gyrochronology hypothesis can be tested by measuring the rotation rates of stars in wide pairs, and verifying that the rotation rates are correlated, which should be true regardless of what their actual ages are. Based on a search of the SUPERBLINK proper motion catalog in the fields to be observed in K2 campaigns 14, 15, and 16, we have identified a total of 194 common proper motion (i.e. co-moving) pairs of stars with angular separations between 4 and 60. Our statistical analysis indicates that >90% of those pairs must be physical binaries in wide orbits (with the rest being chance alignments of unrelated stars). About half the primaries in those wide systems appear to be main-sequence stars of subtypes F-G-K, with the other half consisting of M dwarfs. A majority of the  secondaries, on the other hand, appear to be main-sequence M dwarfs. We propose to use Kepler to observe there stars in wide binary pairs, and measure their rotation rates from an auto-correlation analysis of their light curves. All the pairs should be resolved on the Kepler cameras (4 arcsec pixel size), although some pairs will have overlapping point spread functions and may require pixel-by-pixel analysis. Interestingly, many pairs can be observed in a single Kepler aperture, and thus may only need to be counted as a single target (or may use fewer pixels overall). One prediction of stellar multiplicity models is that very wide companions are often produced by dynamical relaxation in a triple systems, which means that a significant fraction of wide binaries may actually be hierarchical triples, with the inner system having a high probability of being a very tight (spectroscopic or eclipsing) binary star; this prediction will be directly tested with K2, by measuring the detection rate of eclipsing binaries in those pairs.

# Targets requested by this program that have been observed (89)
EPIC ID, RA (J2000) [deg], Dec (J2000) [deg], magnitude, Investigation IDs
204538021, 241.01318, -21.930367, 10.845, GO15041_LC|GO15009_LC|GO15065_LC
204538608, 241.011812, -21.927819, 8.691, GO15041_LC|GO15063_LC|GO15001_LC|GO15044_LC|GO15009_LC|GO15021_LC|GO15065_LC|GO15044_SC
249097408, 235.489079, -26.957855, 15.393, GO15041_LC
249097472, 235.487017, -26.957126, 15.405, GO15041_LC|GO15005_LC
249102785, 230.751573, -26.891792, 16.889, GO15041_LC|GO15005_LC
249103001, 230.747543, -26.889156, 15.882, GO15041_LC|GO15005_LC
249115169, 234.253805, -26.740072, 16.113, GO15041_LC|GO15005_LC
249116371, 234.246913, -26.724811, 12.887, GO15041_LC|GO15009_LC|GO15021_LC
249143399, 231.541179, -26.394453, 15.671, GO15041_LC|GO15074_LC|GO15005_LC
249143586, 231.546807, -26.3918, 15.945, GO15041_LC|GO15074_LC|GO15005_LC|GO15083_LC
249202871, 236.532231, -25.638912, 14.806, GO15041_LC|GO15039_LC
249202898, 236.530962, -25.638569, 14.526, GO15041_LC|GO15039_LC
249207356, 235.84928, -25.58086, 17.339, GO15041_LC|GO15005_LC
249208121, 235.860416, -25.571833, 15.124, GO15041_LC|GO15005_LC
249239834, 232.517655, -25.155938, 13.627, GO15041_LC
249240082, 232.518772, -25.152949, 12.435, GO15041_LC|GO15074_LC|GO15001_LC|GO15009_LC|GO15021_LC|GO15020_LC|GO15083_LC|GO15065_LC
249324893, 234.413185, -24.034526, 15.139, GO15041_LC|GO15005_LC
249324911, 234.41557, -24.034319, 17.07, GO15041_LC|GO15005_LC
249326990, 231.175233, -24.006354, 13.267, GO15041_LC|GO15021_LC|GO15083_LC
249327145, 231.174911, -24.004341, 16.608, GO15041_LC
249340694, 229.850799, -23.836194, 14.547, GO15041_LC|GO15005_LC
249340733, 229.849516, -23.835566, 17.85, GO15041_LC
249362087, 226.366235, -23.557405, 15.87, GO15041_LC|GO15005_LC
249362262, 226.365503, -23.554846, 13.091, GO15041_LC|GO15005_LC|GO15021_LC|GO15083_LC
249380777, 229.501806, -23.311413, 16.752, GO15041_LC|GO15005_LC
249380902, 229.500579, -23.309755, 13.63, GO15041_LC|GO15005_LC|GO15083_LC
249403407, 228.598744, -23.009855, 15.555, GO15041_LC|GO15005_LC
249403486, 228.597709, -23.008793, 14.974, GO15041_LC
249433859, 226.939087, -22.596784, 14.693, GO15041_LC|GO15005_LC
249433928, 226.936044, -22.595968, 13.281, GO15041_LC|GO15001_LC|GO15052_LC|GO15005_LC|GO15021_LC|GO15083_LC|GO15065_LC
249469630, 230.938518, -22.126261, 14.113, GO15041_LC|GO15005_LC|GO15083_LC
249469858, 230.933137, -22.122974, 16.343, GO15041_LC|GO15005_LC
249476249, 226.533845, -22.03849, 14.684, GO15041_LC|GO15001_LC|GO15065_LC
249476366, 226.534973, -22.037312, 15.877, GO15041_LC|GO15065_LC
249481820, 230.19148, -21.966961, 18.066, GO15041_LC
249481914, 230.192903, -21.965593, 16.607, GO15041_LC|GO15005_LC
249547388, 227.887821, -21.146006, 16.354, GO15041_LC|GO15005_LC
249547406, 227.885751, -21.145605, 16.641, GO15041_LC
249564824, 230.634601, -20.936731, 13.276, GO15041_LC|GO15001_LC|GO15052_LC|GO15065_LC
249565084, 230.631562, -20.933171, 14.416, GO15041_LC|GO15005_LC
249571143, 230.685422, -20.857344, 15.255, GO15041_LC|GO15005_LC
249571282, 230.684486, -20.855785, 15.875, GO15041_LC|GO15005_LC
249582901, 230.639774, -20.71264, 9.518, GO15041_LC|GO15068_LC|GO15074_LC|GO15001_LC|GO15009_LC|GO15028_LC|GO15021_LC|GO15065_LC
249583692, 230.643278, -20.70263, 14.492, GO15041_LC|GO15074_LC|GO15005_LC
249597660, 232.950701, -20.533245, 12.349, GO15041_LC|GO15009_LC|GO15052_LC|GO15083_LC
249597784, 232.94942, -20.531738, 12.349, GO15041_LC|GO15009_LC|GO15052_LC|GO15021_LC|GO15020_LC|GO15083_LC
249620050, 237.118236, -20.257532, 18.54, GO15041_LC|GO15039_LC
249620231, 237.116802, -20.255395, 15.079, GO15041_LC|GO15052_LC|GO15039_LC
249627332, 232.927599, -20.164393, 8.836, GO15010_LC|GO15041_LC|GO15063_LC|GO15009_LC|GO15021_LC|GO15065_LC|GO15010_SC
249643917, 230.772608, -19.955545, 16.818, GO15041_LC|GO15005_LC
249644859, 230.783215, -19.943279, 16.047, GO15041_LC|GO15005_LC
249676413, 234.706628, -19.539108, 17.385, GO15041_LC
249677466, 234.698707, -19.525122, 14.882, GO15041_LC|GO15005_LC|GO15083_LC
249680584, 234.0121, -19.484431, 12.619, GO15014_LC|GO15041_LC|GO15068_LC|GO15009_LC|GO15052_LC|GO15005_LC|GO15083_LC
249680619, 234.01452, -19.483902, 12.836, GO15041_LC|GO15009_LC|GO15052_LC|GO15039_LC
249695203, 228.665342, -19.292551, 17.404, GO15041_LC
249695324, 228.663538, -19.290981, 16.63, GO15041_LC|GO15005_LC
249711439, 228.184641, -19.07976, 17.982, GO15041_LC
249711679, 228.185665, -19.076761, 14.875, GO15041_LC|GO15001_LC|GO15065_LC
249770901, 233.207908, -18.284, 12.355, GO15041_LC|GO15001_LC|GO15009_LC|GO15005_LC|GO15083_LC|GO15065_LC
249770990, 233.203066, -18.282797, 14.218, GO15041_LC|GO15005_LC
249806541, 230.197691, -17.814084, 13.496, GO15041_LC|GO15001_LC|GO15052_LC|GO15005_LC|GO15083_LC|GO15065_LC
249806673, 230.19705, -17.81259, 16.178, GO15041_LC
249814215, 236.448597, -17.714151, 16.071, GO15041_LC|GO15005_LC
249814460, 236.448301, -17.711426, 16.799, GO15041_LC|GO15005_LC
249823985, 230.527507, -17.58687, 16.977, GO15041_LC
249824087, 230.526376, -17.585584, 13.966, GO15041_LC|GO15052_LC|GO15005_LC|GO15083_LC
249907358, 236.482283, -16.548519, 12.538, GO15041_LC|GO15009_LC|GO15083_LC
249907380, 236.483667, -16.548205, 12.162, GO15041_LC|GO15009_LC|GO15005_LC
249909370, 228.424735, -16.524693, 16.158, GO15041_LC|GO15005_LC
249909493, 228.423494, -16.523237, 12.8, GO15041_LC|GO15009_LC|GO15052_LC|GO15021_LC|GO15020_LC|GO15083_LC
249929335, 228.594224, -16.293515, 13.038, GO15041_LC|GO15074_LC|GO15005_LC|GO15021_LC|GO15083_LC
249929402, 228.599611, -16.292791, 15.819, GO15041_LC|GO15074_LC|GO15005_LC
250034565, 230.910613, -15.06585, 11.058, GO15041_LC
250034723, 230.909693, -15.064181, 11.058, GO15014_LC|GO15041_LC|GO15001_LC|GO15009_LC|GO15052_LC|GO15005_LC|GO15021_LC|GO15020_LC|GO15083_LC|GO15065_LC
250072828, 237.390492, -14.615495, 12.155, GO15014_LC|GO15041_LC|GO15001_LC|GO15009_LC|GO15052_LC|GO15005_LC|GO15083_LC|GO15065_LC
250073786, 237.393262, -14.604524, 14.05, GO15041_LC|GO15052_LC|GO15005_LC
250079565, 232.853136, -14.535401, 17.303, GO15041_LC|GO15005_LC
250080072, 232.854974, -14.529388, 14.852, GO15041_LC|GO15005_LC|GO15083_LC
250085737, 233.900675, -14.461203, 14.466, GO15041_LC|GO15005_LC
250085830, 233.902462, -14.460197, 15.477, GO15041_LC|GO15005_LC
250121992, 233.007773, -13.999576, 17.424, GO15041_LC
250123029, 233.017244, -13.986259, 12.785, GO15041_LC|GO15009_LC|GO15052_LC|GO15021_LC|GO15020_LC|GO15083_LC
250125877, 232.905327, -13.947049, 13.86, GO15041_LC|GO15052_LC|GO15005_LC|GO15083_LC
250126160, 232.899012, -13.943009, 15.687, GO15041_LC|GO15005_LC
250126593, 235.502765, -13.937082, 15.236, GO15016_LC|GO15041_LC|GO15005_LC|GO15065_LC
250126849, 235.503491, -13.933521, 14.929, GO15041_LC
250140046, 236.242421, -13.751632, 15.303, GO15041_LC|GO15039_LC
250140110, 236.240943, -13.750796, 14.215, GO15041_LC|GO15005_LC|GO15083_LC