Astrophys. J., 723, 1469-1492 (2010/November-2)
Flux calibrations from nearby eclipsing binaries and single stars.
WILSON R.E., VAN HAMME W. and TERRELL D.
Abstract (from CDS):
Eclipsing binaries (EBs) measure distance without need or use for nearby similar objects, with many applications over recent decades. EBs are now considered the most reliable and accurate distance indicators for the very important lower rungs in the cosmic distance ladder, within the Local Group of Galaxies. Among several EB distance algorithms, direct comparison of observed and theoretical fluxes is particularly straightforward, although it requires absolute flux calibrations for which only a modest number of publications exist. Here, we measure UBV RI and uvby flux calibrations and calibration ratios from astronomical objects in ways not previously tried, specifically for EBs, single stars within 80 pc, and the Sun. All of the single stars are below about 6500 K temperature. Interstellar extinction is avoided by a restriction to nearby targets. Some photometric band calibrations in the literature are accurate enough for very good EB distance determinations if star temperatures are accurately known, especially considering that estimated distance has only a square-root dependence on calibration constant, but accurate band-to-band calibration ratios are keys to the combined temperature-distance problem. Band-independent canceling factors (star radii and distances) allow calibration ratio measurement with enhanced accuracy, compared to individual band calibrations. A physical EB model with embedded stellar atmosphere emission optimally matches theory to observations for the binaries. Single star candidates are identified as reliably single if their radial velocity variations are below 100 m/s. For the most part, we find good agreement with some of the previous calibrations and the ratios are improved.
binaries: close - binaries: eclipsing - binaries: spectroscopic - stars: distances
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<Available at CDS (J/ApJ/723/1469): table2.dat table14.dat>
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