view Abstract Citations (17) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS CS 22873-139: A Very Metal-Poor Main-Sequence Spectroscopic Binary With Colors Indicative of Intermediate Age Preston, George W. Abstract CS 22873-139, a metal-deficient ((Fe/H) = -3.1), high-velocity (Vrad = +243 km/s) star with observed UBV colors (B-V = 0.37, U-B = -0.22) that locate it near the main-sequence turnoff of an old metal-poor population (Preston et al. (1991); Beers et al. (1992)), is, in fact, a double-lined spectroscopic binary with a period of 19.16 days, eccentricity e = 0.26, and a mass ratio of approximately 0.88. The observed colors, corrected for reddening, can be matched by those for a family of artificial binaries constructed by use of colors and luminosities taken from isochrones for ages between 3 and 13 Gy, but the strengths of metal lines in the primary and secondary spectra require that the age of the system be less than approximately 8 Gy. The inferred unreddened colors of the primary, (B-V)0,p = 0.30, (U-B)0,p = -0.19, lie blueward of any globular cluster turnoff and near the low-abundance (upper) U-B boundary of BMP stars in the UBV two-color diagram, as discussed by Preston et al. (1994). Were the primary product of binary merger in an initial triple star system, Harrington's (1977) stability criterion requires for the initial close binary a1 less than 5.2 solar radii and P less than 1.5 days. According to Vilhu (1982) such a system will merge in about 109 years, a time much shorter than the main-sequence age deduced for this system, so even if binary merger had taken place the conclusion that CS 22873-139 must be a relatively young metal-poor star is preserved. Publication: The Astronomical Journal Pub Date: December 1994 DOI: 10.1086/117239 Bibcode: 1994AJ....108.2267P Keywords: Binary Stars; Chronology; Main Sequence Stars; Metallicity; Radial Velocity; Stellar Color; Stellar Luminosity; Stellar Spectra; Astronomical Photometry; Echelle Gratings; Hydrogen; Iron; Reflecting Telescopes; Spectrographs; Astronomy; BINARIES: SPECTROSCOPIC; STARS: INDIVIDUAL: CS 22873-139 full text sources ADS | data products SIMBAD (3)