Abstract
We present fits to the broadband photometric spectral energy distributions
(SEDs) of 158 eclipsing binaries (EBs) in the Tycho-2 catalog. These EBs were
selected because they have highly precise stellar radii, effective
temperatures, and in many cases metallicities previously determined in the
literature, and thus have bolometric luminosities that are typically good to
$łesssim$ 10%. In most cases the available broadband photometry spans a
wavelength range 0.4-10 $\mu$m, and in many cases spans 0.15-22 $\mu$m. The
resulting SED fits, which have only extinction as a free parameter, provide a
virtually model-independent measure of the bolometric flux at Earth. The SED
fits are satisfactory for 156 of the EBs, for which we achieve typical
precisions in the bolometric flux of $\approx$ 3%. Combined with the accurately
known bolometric luminosity, the result for each EB is a predicted parallax
that is typically precise to $łesssim$ 5%. These predicted parallaxes---with
typical uncertainties of 200 $\mu$as---are 4-5 times more precise than those
determined by Hipparcos for 99 of the EBs in our sample, with which we find
excellent agreement. There is no evidence among this sample for significant
systematics in the Hipparcos parallaxes of the sort that notoriously afflicted
the Pleiades measurement. The EBs are distributed over the entire sky, span
more than 10 mag in brightness, reach distances of more than 5 kpc, and in many
cases our predicted parallaxes should also be more precise than those expected
from the Gaia first data release. The EBs studied here can thus serve as
empirical, independent benchmarks for these upcoming fundamental parallax
measurements.
Description
Eclipsing Binary Stars as Benchmarks for Trigonometric Parallaxes in the
Gaia Era
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