# Summary of K2 Program GO4069

Title: Exploiting RR Lyrae stars in the C4 and C5 fields of the K2 Mission

PI: Szabo, Robert (Konkoly Observatory of the Hungarian Academy of Sciences)
CoIs: Nemec, James M; Kuehn, Charles August; Plachy, Emese; Molnar, Laszlo; Guggenberger, Elisabeth; Kolenberg, Katrien; Ngeow, Chow-Choong; Jeon, Young-Beom; Moskalik, Pawel A

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 _x0013_ and their optical behavior _x0013_ is of crucial importance to advance our knowledge of galaxy formation and evolution in the Local Group of galaxies and beyond. We plan to study 87 and 90 RR Lyrae stars in the Fields 4&5 with K2's unique capabilities of providing long, uninterrupted, high-precision space photometry. The sample will be used to conduct galactic structure studies and to improve our understanding of dynamical behavior of RR Lyrae stars. Our immediate objectives are: 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 will build up 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 RRd stars, and only a few RRc. 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. After producing light curves from target pixel data we apply standard time-frequency analysis and study  time-dependent features. State-of-the-art numerical hydrocodes and ground-based follow-up observations will be used to interpret the results. Synthetic galactic models  will be computed to compare the galactic location and number of the observed sample with simulations. The proposed project will provide a unique opportunity to better understand these highly variable classical pulsating stars on the horizontal branch and their role in unraveling the formation of our Galaxy.

# Targets requested by this program that have been observed (82)
EPIC ID, RA (J2000) [deg], Dec (J2000) [deg], magnitude, Investigation IDs
210311535, 58.619936, 11.071452, 18.424, GO4069_LC
210322126, 58.64854, 11.407395, 18.771, GO4069_LC
210343581, 60.108515, 12.039104, 19.017, GO4069_LC
210345648, 58.142889, 12.098321, 15.087, GO4069_LC
210361885, 62.215634, 12.541252, 16.588, GO4069_LC
210389601, 58.723087, 13.222803, 18.307, GO4069_LC
210399040, 62.387081, 13.444339, 17.134, GO4069_LC
210418729, 60.482777, 13.888205, 18.927, GO4069_LC
210438688, 57.548881, 14.302434, 17.387, GO4069_LC
210454384, 58.888087, 14.604441, 17.525, GO4069_LC
210457607, 58.348618, 14.665098, 18.561, GO4069_LC
210464181, 54.939685, 14.785275, 17.339, GO4069_LC
210471429, 58.810884, 14.9175, 19.889, GO4069_LC
210475866, 59.606292, 14.997906, 19.442, GO4069_LC
210507908, 54.934893, 15.544499, 19.085, GO4069_LC
210509604, 60.252178, 15.571917, 16.095, GO4069_LC
210511418, 54.454827, 15.601362, 19.661, GO4069_LC
210577318, 52.348397, 16.631229, 18.049, GO4069_LC
210600482, 54.206216, 16.972652, 17.636, GO4069_LC
210607917, 53.350717, 17.076248, 18.898, GO4069_LC
210617106, 53.775331, 17.206639, 19.684, GO4069_LC
210665016, 52.393442, 17.874837, 18.902, GO4069_LC
210678680, 53.282818, 18.063694, 15.161, GO4069_LC
210681941, 57.297641, 18.108371, 18.438, GO4069_LC
210692429, 59.136305, 18.254215, 18.339, GO4069_LC
210697426, 56.123511, 18.32525, 14.786, GO4069_LC
210707203, 57.961599, 18.466192, 18.988, GO4069_LC
210729707, 58.586271, 18.800642, 17.706, GO4069_LC
210733035, 65.293497, 18.850958, 18.679, GO4069_LC
210739713, 66.577806, 18.95301, 15.757, GO4069_LC
210740526, 57.659207, 18.965201, 16.112, GO4069_LC
210746706, 55.108472, 19.058093, 15.095, GO4069_LC
210754711, 66.567775, 19.182075, 16.663, GO4069_LC
210755194, 53.337871, 19.189335, 18.014, GO4069_LC
210763406, 53.312681, 19.31382, 14.651, GO4069_SC|GO4069_LC
210766289, 65.66354, 19.357075, 16.398, GO4069_LC
210796097, 58.836867, 19.809991, 15.58, GO4069_LC
210810957, 62.425298, 20.034501, 15.142, GO4069_LC
210815465, 56.252764, 20.103211, 16.002, GO4069_LC
210830646, 57.082594, 20.335462, 13.751, GO4069_LC|GO4007_LC
210831816, 58.051273, 20.353114, 15.852, GO4069_LC
210839363, 57.69794, 20.46893, 14.392, GO4069_SC|GO4069_LC
210868876, 58.049919, 20.912655, 18.006, GO4069_LC
210889448, 62.124197, 21.226526, 15.422, GO4069_LC
210896547, 53.537632, 21.338052, 16.512, GO4069_LC
210920803, 57.315769, 21.716721, 18.195, GO4069_LC
210925792, 52.675758, 21.798813, 17.712, GO4069_LC
210933539, 52.991105, 21.921016, 15.218, GO4069_SC|GO4069_LC
210994946, 58.963237, 22.894835, 18.278, GO4069_LC
211010071, 62.522502, 23.13463, 16.656, GO4069_LC
211048310, 58.639714, 23.745179, 15.53, GO4069_LC
211069540, 63.954609, 24.084409, 14.948, GO4069_LC|GO4020_LC
211072039, 62.041403, 24.126383, 16.802, GO4069_LC
211077985, 57.15293, 24.220036, 12.992, GO4069_SC|GO4069_LC|GO4029_LC|GO4033_LC|GO4007_LC|GO4086_LC
211091644, 60.135037, 24.430531, 16.262, GO4069_LC
211101195, 60.880069, 24.580213, 15.418, GO4069_LC
220115899, , , , GO4069_LC
220115902, , , , GO4069_LC
220115904, , , , GO4069_LC
220115912, , , , GO4069_LC
220115915, , , , GO4069_LC
220115916, , , , GO4069_LC
220115917, , , , GO4069_LC
220115929, , , , GO4069_LC
220115935, , , , GO4069_LC
220115936, , , , GO4069_LC
220115938, , , , GO4069_LC
220115942, , , , GO4069_LC
220115946, , , , GO4069_LC
220115949, , , , GO4069_LC
220115951, , , , GO4069_LC
220115952, , , , GO4069_LC
220115954, , , , GO4069_LC
220115955, , , , GO4069_LC
220115956, , , , GO4069_LC
220115959, , , , GO4069_LC
220115960, , , , GO4069_LC
220115961, , , , GO4069_LC
220115962, , , , GO4069_LC
220115969, , , , GO4069_LC
220115970, , , , GO4069_LC
220115973, , , , GO4069_LC