IMPROVED VARIABLE STAR SEARCH IN LARGE PHOTOMETRIC DATA SETS: NEW VARIABLES IN CoRoT FIELD LRa02 DETECTED BY BEST II

The CoRoT field LRa02 has been observed with the Berlin Exoplanet Search Telescope II (BEST II) during the southern summer 2007/2008. A first analysis of stellar variability led to the publication of 345 newly discovered variable stars. Now, a deeper analysis of this data set was used to optimize the variability search procedure. Several methods and parameters have been tested in order to improve the selection process compared to the widely used J index for variability ranking. This paper describes an empirical approach to treat systematic trends in photometric data based upon the analysis of variance statistics that can significantly decrease the rate of false detections. Finally, the process of reanalysis and method improvement has virtually doubled the number of variable stars compared to the first analysis by Kabath et al. A supplementary catalog of 272 previously unknown periodic variables plus 52 stars with suspected variability is presented. Improved ephemerides are given for 19 known variables in the field. In addition, the BEST II results are compared with CoRoT data and its automatic variability classification.

[1]  K. Stanek,et al.  Wide‐Field Millimagnitude Photometry with the HAT: A Tool for Extrasolar Planet Detection , 2004, astro-ph/0401219.

[2]  R. W. Noyes,et al.  A PHOTOMETRIC VARIABILITY SURVEY OF FIELD K AND M DWARF STARS WITH HATNet , 2009, 0907.2924.

[3]  Joshua Pepper,et al.  Survey for Transiting Extrasolar Planets in Stellar Systems. IV. Variables in the Field of NGC 1245 , 2006 .

[4]  L. M. Sarro,et al.  Automated supervised classification of variable stars - I. Methodology , 2007, 0711.0703.

[5]  Ralph Neuhäuser,et al.  Transit timing variation and activity in the WASP-10 planetary system , 2010 .

[6]  C. Moutou,et al.  Identification of Variable Stars in CoRoT's First Main Observing Field (LRc1) , 2007 .

[7]  M. Auvergne,et al.  The CoRoT satellite in flight : description and performance , 2009, 0901.2206.

[8]  A. Schwarzenberg-Czerny,et al.  Optimum Period Search: Quantitative Analysis , 1999 .

[9]  H. J. Deeg,et al.  The CoRoT space mission : early results Special feature Ground-based photometry of space-based transit detections : photometric follow-up of the CoRoT mission , 2009 .

[10]  Eike W. Guenther,et al.  The Berlin Exoplanet Search Telescope System , 2003 .

[11]  T. Deeming.  Fourier analysis with unequally-spaced data , 1975 .

[12]  Marc Ollivier,et al.  Automated supervised classification of variable stars in the CoRoT programme. Method and application , 2009 .

[13]  A. Erikson,et al.  A VARIABLE STAR CENSUS IN A PERSEUS FIELD , 2011, 1108.4863.

[14]  A. Erikson,et al.  Characterization of COROT Target Fields with BEST: Identification of Periodic Variable Stars in the IR01 Field , 2007 .

[15]  A. Erikson,et al.  CHARACTERIZATION OF CoRoT TARGET FIELDS WITH BERLIN EXOPLANET SEARCH TELESCOPE. II. IDENTIFICATION OF PERIODIC VARIABLE STARS IN THE LRc2 FIELD , 2007, 0903.0325.

[16]  Licai Deng,et al.  Searching for Variable Stars in the Field of NGC 7789 , 2003 .

[17]  A. Schwarzenberg-Czerny,et al.  Metallicity of clusters from RRab pulsators: results of an automatic analysis , 1998 .

[18]  S. Csizmadia,et al.  The CoRoT space mission : early results Special feature Periodic variable stars in CoRoT field LRa 02 observed with BEST II , 2009 .

[19]  Peter B. Stetson,et al.  ON THE AUTOMATIC DETERMINATION OF LIGHT-CURVE PARAMETERS FOR CEPHEID VARIABLES , 1996 .

[20]  A. Schwarzenberg-Czerny.  Fast and Statistically Optimal Period Search in Uneven Sampled Observations , 1996 .