V474 Car: A RARE HALO RS CVn BINARY IN RETROGRADE GALACTIC ORBIT
- Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627-0171 (United States)
- Swarthmore College, Department of Physics and Astronomy, 500 College Avenue, Swarthmore, PA 19081 (United States)
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)
We report the discovery that the star V474 Car is an extremely active, high velocity halo RS CVn system. The star was originally identified as a possible pre-main-sequence star in Carina, given its enhanced stellar activity, rapid rotation (10.3 days), enhanced Li, and absolute magnitude which places it above the main sequence (MS). However, its extreme radial velocity (264 km s{sup -1}) suggested that this system was unlike any previously known pre-MS system. Our detailed spectroscopic analysis of echelle spectra taken with the CTIO 4 m finds that V474 Car is both a spectroscopic binary with an orbital period similar to the photometric rotation period and metal-poor ([Fe/H] {approx_equal}-0.99). The star's Galactic orbit is extremely eccentric (e {approx_equal} 0.93) with a perigalacticon of only {approx}0.3 kpc of the Galactic center-and the eccentricity and smallness of its perigalacticon are surpassed by only {approx}0.05% of local F/G-type field stars. The observed characteristics are consistent with V474 Car being a high-velocity, metal-poor, tidally locked, chromospherically active binary, i.e., a halo RS CVn binary, and one of only a few such specimens known.
- OSTI ID:
- 21583159
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 141, Issue 4; Other Information: DOI: 10.1088/0004-6256/141/4/140; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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