The Visual Orbit of the 1.1 Day Spectroscopic Binary Sigma2 Coronae Borealis From Interferometry at the Chara Array
GEORGIA STATE UNIV ATLANTA CENTER FOR HIGH ANGULAR RESOLUTION ASTRONOMY
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We present an updated spectroscopic orbit and a new visual orbit for the double-lined spectroscopic binary 2 Coronae Borealis CrB based on radial velocity measurements at the Oak Ridge Observatory in Harvard, MA and interferometer visibility measurements at the Center for High Angular Resolution Astronomy CHARA Array on Mount Wilson in California. sigma2 CrB is composed of two Sun-like stars of roughly equal mass in a circularized orbit with a period of 1.14 days. The long baselines of the CHARA Array have allowed us to resolve the visual orbit for this pain the shortest-period binary yet resolved interferometrically enabling us to determine component masses of 1.137 - 0.037 mass solar mass and 1.090 -36 solar mass. We have also estimated absolute V-band magnitudes of Mv primary 4.35 -0.02 and Mvsecondary 4.74 - 0.02. A comparison with stellar evolution models indicates a relatively young age of 0.1-3 Gyr, consistent with the high-Li abundance measured previously. This pair is the central component of a quintuple system along with another similar-mass star, sigma1 CrB, in a 730-year visual orbit, and a distant M-dwarf binary, sigma CrB C, at a projected separation of 10. We also present differential proper motion evidence to show that components C D ADS 9979C D listed for this system in the Washington Double Star Catalog are optical alignments that are not gravitationally bound to the sigma CrB system.
- Atomic and Molecular Physics and Spectroscopy