New VI photometry of the sdOB binary AA Dor and an improved photometric model

Abstract

New VI CCD photometry, obtained with integration times of 20s, of the sdOB+degenerate-dwarf eclipsing binary system AA Dor has provided new complete light curves with an rms scatter about a mean curve of +/-0.004 mag. These data are analysed with an improved Light2 light curve synthesis code to yield more accurate determinations of the radii of both stars, the orbital inclination, and the flux ratio between the two components. These radii are only a little different from the values derived 25 years ago from less complete data, but the uncertainties on these values are improved by a factor of two. The apparent discrepancy remains between the surface gravity of the sdOB primary star obtained from the light-curve solution with the published spectroscopic orbit and that obtained from NLTE analysis of high-resolution spectra of the sdOB star. The substantial reflection effect in the system is adequately represented by the Light2 code with a bolometric albedo of unity in light curves extending from 0.35 microns to 2.2 microns. However there are differences at individual wavelengths in the derived albedo, which may indicate redistribution of flux from shorter wavelengths into the V and I passbands.

arXiv commentaccepted for publication in MNRAS on 3 June 2003; 8 pages, 8 figures

References in corpus (6)

• The Origin of Subdwarf B Star (I): the Formation Channels
• The origin of sdB stars (II)
• Ultraviolet Radiation from Evolved Stellar Populations -- I. Models
• The binary fraction of extreme horizontal branch stars
• Spectral analysis of sdB stars from the Hamburg Quasar Survey
• The rotational velocity of the sdOB primary of the eclipsing binary system LB 3459 (AA Dor)

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• The new pre-cataclysmic binary PG 2200+085
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• FUSE spectroscopy of sdOB primary of the post common-envelope binary LB 3459 (AA Dor)
• Looking at the bright side - The story of AA Dor as revealed by its cool companion
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• Near-Infrared SOAR Photometric Observations of Post Common Envelope Binaries
• Space observations of AA Doradus provide consistent mass determinations. New HW-Vir systems observed with TESS
• A Dor - An Eclipsing Subdwarf - Brown Dwarf Binary