2009ApJ...695.1527F -
Astrophys. J., 695, 1527-1536 (2009/April-3)
HR 8257: a three-dimensional orbit and basic properties.
FEKEL F.C., BODEN A.F., TOMKIN J. and TORRES G.
Abstract (from CDS):
We have used interferometric and spectroscopic observations of HR 8257 to determine a three-dimensional orbit of the system. The orbit has a period of 12.21345 days and an eccentricity of 0.2895. The masses of the F0 and F2 dwarf components are 1.56 and 1.38 M☉, respectively, with fractional errors of 1.4%. Our orbital parallax of 13.632±0.095 mas, corresponding to a distance of 73.4±0.6 pc, differs from the Hipparcos result by just 2% and has a significantly smaller uncertainty. From our spectroscopic observations and spectral energy distribution modeling we determine the component effective temperatures and luminosities to be Teff(A) = 7030±200 K and Teff(B) = 6560±200 K and LA= 9.4±0.3 L☉ and LB= 4.7±0.2 L☉. The primary rotates pseudosynchronously, while the secondary is not far from its pseudosynchronous rotational velocity. Although both early-F stars are slowly rotating, neither component of this close binary is an Am star. A comparison with evolutionary tracks indicates that the stars are slightly metal poor, and although the components have evolved away from the zero-age main sequence, they are both still dwarfs.
Abstract Copyright:
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Journal keyword(s):
binaries: spectroscopic - stars: fundamental parameters - stars: individual: HR 8257
VizieR on-line data:
<Available at CDS (J/ApJ/695/1527): table2.dat>
Simbad objects:
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