Luminosity function of contact binaries based on the All Sky Automated Survey (ASAS) |
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| Authors: | Slavek M Rucinski |
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| Institution: | Department of Astronomy and Astrophysics, University of Toronto David Dunlap Observatory, PO Box 360, Richmond Hill, Ontario, Canada L4C 4Y6 |
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| Abstract: | The luminosity function for contact binary stars of the W UMa type is evaluated on the basis of the All Sky Automated Survey (ASAS) photometric project covering all stars south of δ=+ 28° within a magnitude range 8 < V < 13 . Lack of colour indices enforced a limitation to 3374 systems with P < 0.562 d (i.e. 73 per cent of all systems with P < 1 d ) where a simplified MV (log P ) calibration could be used. The spatial density relative to the main-sequence FGK stars of 0.2 per cent, as established previously from the Hipparcos sample to V = 7.5 , is confirmed. While the numbers of contact binaries in the ASAS are large and thus the statistical uncertainties small, derivation of the luminosity function required a correction for missed systems with small amplitudes and with orbital periods longer than 0.562 d; the correction, by a factor of 3, carries an uncertainty of about 30 per cent. |
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| Keywords: | binaries: eclipsing stars: evolution |
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