# Summary of K2 Program GO10040

Title: Searching for Extended Exoplanetary Atmospheres Around Active Stars

PI: Jensen, Adam Gabriel (University of Nebraska-Kearney)
CoIs: Cauley, Paul Wilson; Redfield, Seth; Endl, Michael

A key question in studying any planetary atmosphere is what happens at the boundary between the atmosphere and interplanetary space.  This unbound, outermost layer of an atmosphere is called its exosphere.  Several observations of extended atmospheres have been made (e.g., Vidal-Madjar et al. 2003, 2004; Linsky et al. 2010; Schlawin et al. 2010; Lecavelier Des Etangs et al. 2010, 2012; Fossati et al. 2010; Jensen et al. 2012; Cauley et al. 2015, submitted) in hydrogen (both ground-state and excited) and various metals.

Our team detected excited, n=2 hydrogen (through hydrogen alpha absorption) in the exosphere of HD 189733b (Jensen et al. 2012), the first such detection in an exoplanet atmosphere.  Follow-up observations (Cauley et al. 2015, submitted) confirmed this result by detecting exospheric absorption in hydrogen alpha, hydrogen beta, and hydrogen gamma, and also observed a significant pre-transit signal in these lines that is consistent with a bow shock leading the planet by several planetary radii.  Jensen et al. (2012) hypothesized that the excited hydrogen in the exosphere may be correlated with chromospheric activity, as HD 189733b, the only planet in that paper's sample of four planets to show H-alpha absorption, was also the most chromospherically active in the sample (as measured by S_HK and log [R'_HK] indices).

We propose to search for planets around stars which are candidates for chromospheric activity in the Kepler Campaign 8 and 10 fields.  The initial (but not exhaustive) basis for our target list is the tens of possible targets in the approximate fields listed in the Radial Velocity Experiment (RAVE) Survey's catalogue of chromospherically active stars (Zerjal et al. 2013).  Looking for planets around active stars with radial velocity methods is often disfavored because the stellar noise limits RV precision.  However, this makes the transit method the more important way to detect planets in these cases.  Furthermore, if any of these stars do have a transiting planet, they will be excellent potential candidates for follow-up spectroscopy with the large ground-based telescopes (Keck I, Hobby-Eberly Telescope) that our team has used in the past to detect exospheric absorption.  The goal of follow-up spectroscopic observations would be to search for excited hydrogen absorption from an exosphere, including possible pre-transit signals.  As a secondary science product, many of these active stars will have light curves worth studying on their own for stellar astrophysics purposes.

# Targets requested by this program that have been observed (62)
EPIC ID, RA (J2000) [deg], Dec (J2000) [deg], magnitude, Investigation IDs
201076871, 182.257958, -7.251087, 11.509, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC
201087710, 182.421755, -6.941015, 11.463, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC
201092727, 181.415923, -6.802351, 11.294, GO10068_LC|GO10077_LC|GO10040_LC|GO10066_LC|GO10042_LC|GO10036_LC
201095279, 181.232731, -6.729476, 12.166, GO10040_LC|GO10042_LC|GO10036_LC
201098934, 181.578987, -6.623276, 11.455, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC
201107186, 180.913366, -6.388321, 10.658, GO10068_LC|GO10051_LC|GO10077_LC|GO10040_LC|GO10066_LC
201114216, 179.771567, -6.194987, 9.913, GO10068_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10042_LC
201115206, 183.72838, -6.169205, 12.01, GO10032_LC|GO10077_LC|GO10040_LC|GO10042_LC
201121625, 181.076462, -5.994116, 11.748, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10036_LC
201131505, 181.110064, -5.749937, 10.439, GO10068_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC|GO10042_LC
201196025, 184.000172, -4.195736, 11.84, GO10040_LC|GO10042_LC|GO10036_LC
201235531, 180.097329, -3.429183, 14.603, GO10906_LC|GO10012_LC|GO10040_LC|GO10042_LC
201242698, 184.806215, -3.319789, 8.427, GO10013_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10002_LC|GO10002_SC
201245218, 182.102146, -3.281975, 12.802, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10042_LC
201258223, 183.120178, -3.084473, 7.29, GO10077_LC|GO10040_LC|GO10031_LC
201270840, 180.742099, -2.892532, 10.664, GO10040_LC|GO10042_LC|GO10036_LC
228711106, 189.685472, -10.802669, 10.518, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC|GO10042_LC
228713899, 184.999726, -10.660541, 11.957, GO10068_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC
228737206, 183.405355, -9.51338, 7.416, GO10051_LC|GO10077_LC|GO10040_LC|GO10031_LC|GO10002_LC|GO10002_SC
228738737, 183.464496, -9.440583, 12.313, GO10040_LC|GO10042_LC
228739714, 182.701113, -9.397219, 7.311, GO10063_LC|GO10040_LC|GO10042_LC|GO10031_LC|GO10036_LC
228742414, 185.840873, -9.269132, 12.243, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10042_LC
228743394, 189.227204, -9.224662, 11.355, GO10040_LC|GO10042_LC
228743532, 186.604768, -9.218662, 12.491, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC
228745504, 183.515803, -9.123514, 10.826, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC
228746202, 188.639379, -9.094061, 11.835, GO10056_LC|GO10032_LC|GO10040_LC|GO10059_LC|GO10042_LC
228746879, 188.639637, -9.063005, 10.682, GO10068_LC|GO10077_LC|GO10040_LC|GO10059_LC|GO10042_LC
228751843, 192.879508, -8.841724, 12.053, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10042_LC
228756384, 190.836924, -8.639815, 10.415, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC
228757317, 190.972298, -8.597275, 11.637, GO10040_LC|GO10066_LC|GO10042_LC
228759874, 185.120566, -8.487729, 10.338, GO10068_LC|GO10077_LC|GO10040_LC
228770476, 192.900065, -8.026702, 11.661, GO10032_LC|GO10040_LC|GO10066_LC|GO10042_LC
228771056, 186.311545, -8.000922, 11.451, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC|GO10042_LC
228780467, 191.312007, -7.597888, 11.291, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10042_LC
228783556, 183.505733, -7.464439, 12.14, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC
228787818, 186.409469, -7.284588, 10.399, GO10040_LC|GO10066_LC
228789925, 192.50724, -7.197474, 8.109, GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10031_LC|GO10002_LC|GO10002_SC
228807607, 186.752342, -6.462376, 10.268, GO10068_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC|GO10042_LC
228815627, 184.151417, -6.127624, 11.603, GO10056_LC|GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10042_LC
228837554, 188.636441, -5.214527, 10.337, GO10068_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC|GO10042_LC
228841205, 190.405319, -5.061971, 11.156, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC|GO10042_LC|GO10033_LC
228845138, 186.540382, -4.897973, 10.413, GO10051_LC|GO10032_LC|GO10040_LC|GO10066_LC|GO10042_LC|GO10036_LC
228848467, 190.2546, -4.756446, 9.631, GO10068_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10036_LC|GO10033_LC
228850202, 187.046409, -4.684306, 10.599, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC|GO10042_LC
228854380, 186.319983, -4.506887, 10.108, GO10068_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC
228855236, 189.145315, -4.470178, 10.825, GO10068_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10066_LC|GO10033_LC
228858068, 185.691405, -4.348851, 12.689, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10042_LC
228860193, 190.71166, -4.260674, 12.05, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10042_LC|GO10033_LC
228861232, 186.2297, -4.217112, 11.588, GO10051_LC|GO10077_LC|GO10040_LC|GO10042_LC
228867240, 190.761682, -3.966388, 11.273, GO10068_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10033_LC
228869207, 186.295257, -3.876315, 11.584, GO10032_LC|GO10077_LC|GO10040_LC|GO10042_LC
228872177, 190.449444, -3.749694, 10.434, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10033_LC
228875644, 185.949766, -3.688995, 10.945, GO10068_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC
228882146, 189.415, -3.582246, 11.817, GO10056_LC|GO10040_LC
228883845, 185.812036, -3.554197, 11.841, GO10040_LC|GO10042_LC|GO10036_LC
228884634, 186.757106, -3.54064, 10.123, GO10068_LC|GO10013_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10042_LC|GO10033_LC
228885036, 190.001269, -3.533878, 10.742, GO10056_LC|GO10040_LC|GO10042_LC|GO10008_LC
228887214, 186.128868, -3.498172, 10.031, GO10068_LC|GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10033_LC
228899205, 186.914408, -3.289609, 11.677, GO10068_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10033_LC
228972691, 189.217231, -1.983561, 12.395, GO10056_LC|GO10068_LC|GO10040_LC|GO10042_LC|GO10008_LC
229095758, 187.726184, 0.664783, 8.781, GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC
229110376, 188.285029, 1.043995, 8.198, GO10051_LC|GO10032_LC|GO10077_LC|GO10040_LC|GO10002_LC|GO10002_SC