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J/MNRAS/416/2477    STEREO observations of variable stars    (Wraight+, 2011)

STEREO observations of stars and the search for exoplanets. Wraight K.T., White G.J., Bewsher D., Norton A.J.. <Mon. Not. R. Astron. Soc. 416, 2477 (2011)> =2011MNRAS.416.2477W
ADC_Keywords: Binaries, eclipsing ; Photometry, CCD Mission_Name: STEREO Keywords: methods: data analysis - binaries: eclipsing - space vehicles: instruments - stars: individual: HD 213597 - stars: individual: NSV 7359 - stars: individual: V471 Tau Abstract: The feasibility of using data from the NASA STEREO mission for variable star and asteroseismology studies has been examined. A data analysis pipeline has been developed that is able to apply selected algorithms to the entire database of nearly a million stars to search for signs of variability. An analysis limited to stars of magnitude 10.5 has been carried out, which has resulted in the extraction of 263 eclipsing binaries (EBs), of which 122 are not recorded as such in the SIMBAD online database. The characteristics of the STEREO observations are shown to be extremely well-suited to variable star studies with the ability to provide continuous phase coverage for extended periods as well as repeated visits that allow both short and long term variability to be observed. This will greatly inform studies of particular stars, such as the pre-cataclysmic variable V471 Tau, as well as entire classes of stars, including many forms of rotational variability. The high-precision photometry has also revealed a potentially substellar companion to a bright (R=7.5mag) nearby star (HD 213597), detected with 5 sigma significance. This would provide a significant contribution to exoplanet research if follow-up observations ascertain the mass to be within the planetary domain. Some particularly unusual EBs from the recovered sample are discussed, including a possible reclassification of a well-known star as an EB rather than a rotational variable (HR 7355) and several particularly eccentric systems, including very long-period EBs. Description: Description of the analysis of stars brighter than R=10.5mag from the Heliospheric Imager on the STEREO-Ahead spacecraft (STEREO/HI-1A). Analysis of the effectiveness of the different algorithms used. Analysis of different trends amongst the sample of EBs detected. Photometric lightcurves of several individual stars of interest given, including all measurably eccentric EBs detected. Statistics for 263 eclipsing binaries. Lightcurves for all EBs provided in supporting information in the electronic version of the paper. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file tablea1.dat 167 263 Statistics for 263 EBs and the significance of their detection by different algorithms
Byte-by-byte Description of file: tablea1.dat
Bytes Format Units Label Explanations
1- 10 F10.6 deg RAdeg Right Ascension (J2000) 12- 22 F11.7 deg DEdeg Declination (J2000) 24- 28 F5.3 mag PED Primary Eclipse Depth 30- 37 F8.5 d Per Period 39- 46 F8.5 mag Wmag Weighted mean magnitude (4) 48- 54 F7.5 --- BLS Box-Least-Squares variability index (Kovacs et al., 2002A&A...391..369K) 56- 69 F14.7 --- SID Stetson variability index 71- 78 F8.4 --- LS Peak Lomb-Scargle power (1982ApJ...263..835S) 80- 84 F5.3 --- ecosw ?=- Minimum eccentricity |e*cos(ω)| 86- 90 F5.3 --- e_ecosw ?=- rms uncertainty on |e*cos(ω)| 92-102 A11 --- SpType MK spectral type (1) 104-126 A23 --- SimID ID of closest star in SIMBAD at RA/DE 128-151 A24 --- SimID2 ID of alternative nearby star (2) 153 I1 --- EB [0,1] 1 = known eclipsing binary flag 155-166 F12.6 d MJD mid-eclipse Modified Julian Date 167 A1 --- Note [*] Note for CCDM J03295+2107 (3)
Note (1): The spectral type given is of the star in SIMBAD closest to the RA/DE coordinates (See also Note (2)). Note (2): Due to the large (70") pixel scale of the Heliospheric Imager it is not always possible to be confident of which star is responsible for the variability detected. When a nearby star may potentially be the source of the variability, its identity is recorded here. If either of these stars is recorded as an eclipsing binary in SIMBAD, or the references imply or state they are, then the Known EB flag is set to 1. Note (3): For CCDM J03295+2107AB (row 11), has since been found from an analysis including data from the STEREO-Behind spacecraft (STEREO/HI-1B) data to be an eccentric eclipsing binary with a period of 16.6291 days and a minimum eccentricity (|e*cos(w)|) of 0.34±0.01. The original published version has about one third of this period, as the analysis instead identified by mistake the time between primary and secondary eclipses. The additional data from STEREO/HI-1B also allowed a refinement of the mid-eclipse time to 54212.12009 MJD. Tablea1.dat contains these new data, and then differs from published version in the paper. Note (4): the filter bandpass is 630-730nm, with some contributions around 400 and 950nm)
Acknowledgements: Karl Wraight, k.t.wraight(at)
(End) K.T. Wraight [OU, England], Patricia Vannier [CDS] 22-Sep-2011
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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