# Summary of K2 Program GO10037

Title: Pulsation dynamics and galactic structure studies using K2 RR Lyrae stars

PI: Szabo, Robert (Konkoly Observatory of the Hungarian Academy of Sciences)
CoIs: Plachy, Emese; Banyai, Evelin; Molnar, Laszlo; Kolenberg, Katrien

Abstract. Space observations of RR Lyrae stars delivered an avalanche of discoveries including new dynamical phenomena that helped to study the internal structure and evolution of horizontal-branch stars. These objects are excellent galactic structure tracers and distance indicators, therefore understanding their dynamics is of crucial importance to advance our knowledge of galaxy formation and evolution in the Local Group of galaxies and beyond. In this proposal we plan to study ~110 RR Lyrae stars in Field 8 and ~230 in Field 10 in long cadence and 5-5 in short cadence mode. The sample will be used to conduct galactic structure studies and to improve our understanding of the pulsational dynamics of RR Lyrae stars.

Research goals. 1. Study the Galactic structure and history by obtaining distances to RR Lyrae stars and determine their spatial distribution (halo streams, over-densities). During the K2 Mission we are building a unique database from field to field covering different parts of our Galaxy, to yield an unprecedented photometric RR Lyrae sample which will form the base of galactic structure studies and near-field cosmology. 2. Statistical analysis of various dynamical phenomena (double-mode pulsation, Blazhko-modulation, period-doubling, low-dimensional chaos, nonradial modes) and their occurrence rates to better understand their origin and their effect on distance determination. This can only be accomplished with K2. 3. Analyze in detail all RR Lyrae light curves, especially overtone and classical double-mode pulsators. The original Kepler field contained no double-mode RR Lyrae stars, and only a few overtone pulsators. In previous fields K2 observed 5 RRd and 24 RRc, but with Fields 8 &10 we will be able to increase their number by a factor of 2 and 3, respectively. This will aid the investigation of dynamical phenomena (resonances, mode interactions) that may be important in other types of pulsating stars, but can be best studied only in large-amplitude stars and with space photometry, and will also help to derive masses for RRd stars.

Methods. We produce light curves from target pixel data (PyKE and own software), then apply corrections, trend-filtering, outlier removal, etc. Standard time-frequency analysis (by e.g. Period04) and study of time-dependent features are envisaged. Metallicities will be derived from empirical relations calibrated with high-resolution Keck/CFHT spectra. State-of-the-art numerical hydrocodes (Florida-Budapest, Warsaw) will be used to interpret the results. Synthetic galactic models (TRILEGAL) will be used to compare the galactic location and number of the observed sample with simulations.
Targets. Approximately 100 and 230 RR Lyrae stars will be proposed (5-5 stars per field for short cadence observations). Although the RR Lyrae stars are faint due to their distances, the majority falling between 15 and 19 mag, where Kepler's precision is still high for these objects. 

Experience of team members. Our team consists of members of the Working Group#7 (RR Lyrae and Cepheids) of the Kepler Asteroseismic Science Consortium, who have been working on Kepler data (also preparation and target selection) since the launch of the original mission. Our scientists are experts on data reduction, pixel photometry, light curve and time-frequency analysis, as well as theorists performing numerical hydrodynamical modeling. We developed dedicated software and routinely analyze Kepler and K2 data, and published 15+ Kepler RR Lyrae papers in high-impact journals. The group has access to ground-based follow-up (multi- color photometric and spectroscopic) instruments in Taiwan, Korea, USA, Canada and Hungary to complement space-based observations. We are currently finalizing two K2 papers featuring the first unambiguous detection of the Blazhko effect beyond the Magellanic Clouds, and a summary paper on RR Lyrae stars observed in the K2 Engineering Field.

# Targets requested by this program that have been observed (225)
EPIC ID, RA (J2000) [deg], Dec (J2000) [deg], magnitude, Investigation IDs
201085427, 181.58985, -7.006099, 17.784, GO10037_LC
201103700, 183.136475, -6.486584, 18.077, GO10037_LC
201121817, 179.590543, -5.989334, 17.489, GO10037_LC
201124459, 179.641354, -5.923987, 15.398, GO10037_LC|GO10037_SC
201128971, 180.766623, -5.811473, 18.41, GO10037_LC
201129022, 183.550878, -5.810404, 14.23, GO10037_LC
201132450, 182.582519, -5.728119, 14.446, GO10037_LC
201133852, 183.43368, -5.694206, 16.269, GO10037_LC
201146494, 184.416677, -5.378664, 17.75, GO10037_LC
201146611, 181.11049, -5.375972, 15.997, GO10037_LC
201150676, 180.297895, -5.279718, 17.784, GO10037_LC
201152424, 182.52053, -5.238505, 18.173, GO10037_LC
201161411, 180.335992, -5.02332, 16.004, GO10037_LC
201169634, 181.295266, -4.825968, 14.48, GO10037_LC
201185585, 183.365618, -4.443702, 16.949, GO10037_LC
201187587, 182.663461, -4.395369, 17.809, GO10037_LC
201191850, 184.975383, -4.293714, 15.319, GO10037_LC
201199013, 183.166641, -4.125595, 15.957, GO10037_LC
201199981, 184.522155, -4.103376, 18.067, GO10037_LC
201200192, 184.39532, -4.098448, 16.233, GO10037_LC
201200243, 181.317576, -4.097118, 16.387, GO10037_LC
201206717, 179.860115, -3.945872, 18.125, GO10037_LC
201220769, 182.787324, -3.649736, 16.054, GO10037_LC
201221065, 183.850591, -3.645403, 18.037, GO10037_LC
201226859, 180.40397, -3.557983, 17.437, GO10037_LC
201243594, 181.448227, -3.306707, 16.674, GO10037_LC
201246467, 180.864381, -3.262432, 16.161, GO10037_LC
201253413, 183.286876, -3.15609, 17.709, GO10037_LC
201254085, 182.10812, -3.145929, 18.338, GO10037_LC
201263436, 183.720497, -3.004227, 17.885, GO10037_LC
201297970, 180.816091, -2.481512, 17.906, GO10037_LC
201315896, 181.517212, -2.215951, 15.155, GO10037_LC
201318343, 181.087225, -2.178387, 16.748, GO10037_LC
201337319, 180.632365, -1.895714, 16.508, GO10037_LC
201338728, 180.215495, -1.875085, 18.146, GO10037_LC
201342448, 186.065286, -1.820554, 17.888, GO10037_LC
201344269, 180.194463, -1.7925, 17.981, GO10037_LC
201344920, 183.876287, -1.782828, 18.496, GO10037_LC
201359919, 185.116985, -1.557194, 14.183, GO10037_LC
201383569, 182.001568, -1.209466, 15.855, GO10037_LC
201385473, 182.332279, -1.179817, 18.049, GO10037_LC
201389460, 183.730138, -1.120125, 18.138, GO10037_LC
201390991, 186.044666, -1.097921, 18.071, GO10037_LC
201395405, 183.373433, -1.031064, 17.558, GO10037_LC
201395729, 184.925823, -1.026176, 18.486, GO10037_LC|GO10037_SC
201405034, 183.865843, -0.882381, 15.777, GO10037_LC|GO10031_LC
201410425, 182.293487, -0.799734, 17.67, GO10037_LC
201411146, 182.13065, -0.788359, 17.064, GO10037_LC
201413544, 181.911199, -0.75282, 15.926, GO10037_LC
201416299, 184.679301, -0.710766, 17.919, GO10037_LC
201416966, 183.808104, -0.700456, 14.441, GO10037_LC
201433531, 182.146132, -0.456759, 10.334, GO10032_LC|GO10037_LC|GO10077_LC|GO10066_LC|GO10033_LC|GO10028_LC|GO10037_SC
201440678, 181.212539, -0.351808, 17.238, GO10037_LC
201458397, 183.965301, -0.0986, 16.842, GO10037_LC
201460347, 181.878916, -0.070078, 17.651, GO10037_LC
201476942, 183.568089, 0.17412, 17.371, GO10037_LC
201490066, 184.036086, 0.373889, 17.266, GO10037_LC
201519136, 185.412109, 0.816646, 17.947, GO10037_LC|GO10037_SC
201550621, 185.719813, 1.297582, 12.626, GO10037_LC|GO10077_LC
201650804, 185.441164, 2.828462, 15.545, GO10037_LC
201665943, 184.722288, 3.074957, 17.375, GO10037_LC
201666354, 185.625041, 3.081811, 16.288, GO10037_LC
228710407, 187.89904, -10.838207, 15.393, GO10037_LC
228711572, 188.399934, -10.78054, 15.508, GO10037_LC
228715595, 184.864472, -10.571358, 16.658, GO10037_LC
228722434, 184.508592, -10.232274, 15.502, GO10037_LC
228723194, 189.641304, -10.196617, 14.523, GO10037_LC
228724588, 182.487545, -10.127594, 17.455, GO10037_LC
228731765, 187.836269, -9.77903, 16.854, GO10037_LC
228734213, 183.294003, -9.656899, 16.596, GO10037_LC
228734699, 189.187283, -9.634345, 16.56, GO10037_LC
228737749, 186.573397, -9.488132, 15.242, GO10037_LC
228740466, 185.66568, -9.359626, 17.882, GO10037_LC
228741051, 185.54049, -9.331792, 17.194, GO10037_LC
228742497, 184.752184, -9.26505, 16.228, GO10037_LC
228743780, 189.538168, -9.205894, 14.132, GO10037_LC
228744634, 181.866137, -9.165739, 15.798, GO10037_LC
228756284, 182.666684, -8.644397, 16.331, GO10037_LC
228757559, 185.008362, -8.586194, 15.292, GO10037_LC
228759724, 182.340096, -8.494021, 17.175, GO10037_LC
228763070, 192.257565, -8.346915, 15.355, GO10037_LC|GO10037_SC
228763080, 192.018812, -8.346497, 12.517, GO10037_LC|GO10077_LC
228767767, 182.1326, -8.143204, 17.297, GO10037_LC
228769382, 192.343591, -8.074637, 14.612, GO10037_LC
228777682, 186.831114, -7.721016, 17.816, GO10037_LC
228778489, 191.237992, -7.686026, 16.186, GO10037_LC
228779200, 191.450737, -7.654814, 17.464, GO10037_LC
228779358, 185.38533, -7.647805, 16.183, GO10037_LC
228784317, 186.553982, -7.431469, 16.753, GO10037_LC
228785948, 184.241956, -7.363681, 15.847, GO10037_LC
228793624, 183.792932, -7.048245, 15.771, GO10037_LC
228798037, 186.723895, -6.86302, 17.413, GO10037_LC
228798116, 190.981171, -6.859771, 17.796, GO10037_LC
228800773, 191.092577, -6.750381, 18.255, GO10037_LC
228802296, 191.581253, -6.68403, 16.814, GO10037_LC
228803883, 191.10372, -6.615557, 16.305, GO10037_LC
228806239, 185.278756, -6.520079, 16.671, GO10037_LC
228818738, 187.021907, -5.998833, 13.589, GO10037_LC|GO10077_LC|GO10037_SC
228830506, 189.781365, -5.506041, 16.074, GO10037_LC
228838306, 188.412474, -5.182604, 17.325, GO10037_LC
228839859, 188.758816, -5.117139, 17.415, GO10037_LC
228842305, 187.182191, -5.016208, 16.372, GO10037_LC
228843578, 188.989431, -4.963744, 17.041, GO10037_LC
228845601, 185.987047, -4.880043, 15.991, GO10037_LC
228858758, 187.763554, -4.32063, 14.647, GO10037_LC
228871058, 190.585099, -3.79261, 16.067, GO10037_LC
228878890, 189.487124, -3.635686, 16.055, GO10037_LC
228881816, 185.76472, -3.587885, 15.279, GO10037_LC
228883462, 189.072777, -3.560288, 19.302, GO10037_LC
228889770, 187.443279, -3.455962, 18.708, GO10037_LC
228891282, 189.139354, -3.430062, 16.698, GO10037_LC
228897796, 187.386214, -3.314539, 18.047, GO10037_LC
228900184, 187.884532, -3.272701, 16.6, GO10037_LC
228921961, 185.985752, -2.891247, 16.463, GO10037_LC
228924887, 191.975252, -2.840184, 18.321, GO10037_LC
228926067, 191.843063, -2.818729, 15.312, GO10037_LC
228930895, 189.385761, -2.734437, 16.177, GO10037_LC
228939126, 191.088355, -2.585404, 15.769, GO10037_LC
228944874, 188.023258, -2.483892, 17.31, GO10037_LC
228948127, 189.113835, -2.425708, 11.983, GO10037_LC|GO10077_LC|GO10037_SC
228952519, 192.124574, -2.346759, 18.193, GO10037_LC
228961401, 189.490411, -2.191526, 19.304, GO10037_LC
228964090, 193.385543, -2.141572, 14.05, GO10037_LC
228965138, 191.700323, -2.121921, 15.518, GO10037_LC|GO10031_LC
228967411, 191.123771, -2.080615, 14.5, GO10037_LC
228969131, 193.758426, -2.048471, 16.69, GO10037_LC
228971664, 193.022387, -2.001966, 16.784, GO10037_LC
228976569, 184.597066, -1.91357, 18.374, GO10037_LC
228977178, 193.17365, -1.902497, 18.734, GO10037_LC
228981107, 190.415865, -1.830326, 13.962, GO10037_LC
228984615, 193.807543, -1.768389, 16.693, GO10037_LC
228995882, 187.293916, -1.566588, 15.108, GO10037_LC
228996166, 190.546571, -1.561053, 16.413, GO10037_LC
228998377, 187.928575, -1.520586, 17.736, GO10037_LC
229001203, 190.960796, -1.472582, 17.345, GO10037_LC
229003251, 189.385017, -1.434571, 10.912, GO10037_LC|GO10077_LC
229004894, 185.336098, -1.403848, 17.89, GO10037_LC
229005824, 190.963439, -1.387353, 14.976, GO10037_LC
229013350, 187.016096, -1.248519, 15.264, GO10037_LC
229015634, 186.423329, -1.19776, 18.638, GO10037_LC
229021597, 192.278709, -1.072731, 14.593, GO10037_LC
229025772, 186.95075, -0.979487, 17.004, GO10037_LC
229026332, 186.93041, -0.965308, 17.378, GO10037_LC
229027107, 191.029676, -0.946944, 16.431, GO10037_LC
229027984, 190.865788, -0.926917, 15.689, GO10037_LC
229029820, 187.946609, -0.884437, 16.588, GO10037_LC
229031537, 191.208871, -0.844377, 14.879, GO10037_LC|GO10037_SC
229040738, 187.149624, -0.644384, 17.544, GO10037_LC
229044496, 186.761178, -0.55545, 15.282, GO10037_LC
229054355, 187.8889, -0.336204, 17.283, GO10037_LC
229072887, 190.061073, 0.095427, 18.177, GO10037_LC
229075488, 190.738743, 0.155979, 15.53, GO10037_LC
229079124, 184.515487, 0.246915, 17.854, GO10037_LC
229082399, 189.624086, 0.333746, 18.903, GO10037_LC
229095488, 188.584122, 0.656947, 14.915, GO10037_LC
229102136, 190.193995, 0.83504, 17.82, GO10037_LC
229105036, 187.981819, 0.908571, 14.059, GO10037_LC
229108491, 188.33298, 0.995698, 19.063, GO10037_LC
229117038, 190.402719, 1.218391, 16.959, GO10037_LC
229118327, 186.512442, 1.251991, 15.31, GO10037_LC
229134696, 187.167664, 1.635245, 17.173, GO10037_LC
229134937, 191.531258, 1.64138, 18.941, GO10037_LC
229138826, 188.318165, 1.733322, 17.859, GO10037_LC
229139563, 188.835981, 1.750175, 17.421, GO10037_LC
229145656, 187.117293, 1.894992, 17.81, GO10037_LC
229150262, 188.306996, 2.008111, 17.476, GO10037_LC
229152137, 190.728492, 2.056057, 16.992, GO10037_LC
229152498, 185.65141, 2.065906, 18.05, GO10037_LC
229152942, 186.81709, 2.077042, 18.737, GO10037_LC
229153968, 188.248146, 2.103973, 16.714, GO10037_LC
229167571, 187.738336, 2.470845, 17.495, GO10037_LC
229174057, 186.844837, 2.651093, 16.472, GO10037_LC
229177052, 187.930781, 2.739028, 15.172, GO10037_LC
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