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J/ApJ/731/17   Variability of low-mass stars in SDSS Stripe 82   (Becker+, 2011)

Periodic variability of low-mass stars in Sloan Digital Sky Survey Stripe 82. Becker A.C., Bochanski J.J., Hawley S.L., Ivezic Z., Kowalski A.F., Sesar B., West A.A. <Astrophys. J., 731, 17 (2011)> =2011ApJ...731...17B
ADC_Keywords: Photometry, SDSS ; Stars, variable ; Stars, late-type ; Binaries, eclipsing ; Stars, white dwarf ; Spectral types Keywords: binaries: eclipsing - brown dwarfs - stars: low-mass Abstract: We present a catalog of periodic stellar variability in the "Stripe 82" region of the Sloan Digital Sky Survey. After aggregating and re-calibrating catalog-level data from the survey, we ran a period-finding algorithm (Supersmoother) on all point-source light curves. We used color selection to identify systems that are likely to contain low-mass stars, in particular M dwarfs and white dwarfs. In total, we found 207 candidates, the vast majority of which appear to be in eclipsing binary systems. The catalog described in this paper includes 42 candidate M dwarf/white dwarf pairs, four white dwarf pairs, 59 systems whose colors indicate they are composed of two M dwarfs and whose light-curve shapes suggest they are in detached eclipsing binaries, and 28 M dwarf systems whose light-curve shapes suggest they are in contact binaries. We find no detached systems with periods longer than 3 days, thus the majority of our sources are likely to have experienced orbital spin-up and enhanced magnetic activity. Description: While the majority of SDSS imaging resulted in a single epoch of data, imaging of SDSS Stripe 82 was undertaken during commissioning (starting in 1998) and repeated intermittently throughout the survey. Stripe 82 covers 300deg2 of the SDSS footprint, with -60°<RA<+60° (20hr to 4hr in right ascension) and -1.267°<DEC<+1.267° in declination. Stripe 82 was imaged every clear night for 3 months of the year as part of the SDSS-II Supernova Survey from 2005 to 2007 (Frieman et al. 2008AJ....135..338F). We have followed the prescription of Ivezic et al. (2007AJ....134..973I) in re-calibrating the publicly available Stripe 82 data set. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 66 207 Summary of the 207 periodic variables in SDSS Stripe 82 table2.dat 57 207 System classifications for all 207 of our periodic objects
See also: II/294 : SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009) J/A+A/510/A100 : Four new SDSS eclipsing systems (Southworth+, 2010) J/ApJS/186/233 : Variable point sources in SDSS stripe 82. I. (Bhatti+, 2010) J/ApJS/185/32 : First-year SDSS-II SN results (Kessler+, 2009) J/AJ/135/348 : SDSS-II SNe survey: search and follow-up (Sako+, 2008) J/AJ/136/2306 : SDSS-II Supernova survey, 2005 (Holtzman+, 2008) J/MNRAS/382/515 : SDSS ultracool and halo WD candidates (Vidrih+, 2007) : SDSS home page : SDSS Stripe 82 Variable Stars project web site Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 A4 --- --- [SDSS] 6- 24 A19 --- SDSS SDSS name ( 26- 30 F5.2 mag rmag Mean r-band magnitude (1) 32- 36 F5.2 mag u-g Mean (u-g) color index (1) 38- 42 F5.2 mag g-r Mean (g-r) color index (1) 44- 48 F5.2 mag r-i Mean (r-i) color index (1) 50- 54 F5.2 mag i-z Mean (i-z) color index (1) 56- 64 F9.7 d Per Derived period for the system (2) 66 A1 --- q_Per [ABC] Quality of the folded light curve (3)
Note (1): The mean r-band magnitude and mean colors of the system, de-reddened using the prescription of Schlegel et al. (1998ApJ...500..525S). Note (2): Our derived period for the system, defined such that the folded light curve has two maxima and minima. Note (3): Quality estimate of the folded light curve, described in Section 3, as follows: A = best candidates: with complete and even phase coverage, and a smooth folded light-curve shape. B = typical candidates: with some gaps in the phase coverage leading to some uncertainty in the overall light-curve shape, but with enough coverage that the periods are likely correct. C = lower signal-to-noise ratio (S/N) candidates: with noisy light curves and larger-than-average gaps in phase coverage.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 A4 --- --- [SDSS] 6- 24 A19 --- SDSS SDSS name ( 26- 30 A5 --- Col MK color class (4) 32- 36 A5 --- Sp MK spectral class (5) 38- 43 A6 --- gClass Binary class g (6) 45- 50 A6 --- rClass Binary class r (6) 52- 57 A6 --- iClass Binary class i (6)
Note (4): Mean colors are used to estimate a color-based classification using the M dwarf color-spectral-type relationships of Kowalski et al. (2009AJ....138..633K). Systems with u-g<1.8 also likely contain a white dwarf (WD). Note (5): Twenty-nine of the systems have spectra available from SDSS, and are used to make a spectral classification using the software of Covey et al. (2007, Cat. J/AJ/134/2398). Note (6): We use the folded light-curve shape-based methods of Pojmanski (2002, Cat. II/264) and Rucinski (1997AJ....113..407R) to constrain the geometry of the system using the g-, r-, and i-band data. This binary class may be contact eclipsing (EC, EC*), semi-detached (ESD), or detached (ED, ED*). We have highest confidence in the classification of those systems where Binary Classg=Binary Classr=Binary Classi, which represent the subset of systems used in the analysis of Section 5.
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 16-Oct-2012
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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