ANALYSIS OF DETACHED ECLIPSING BINARIES NEAR THE TURNOFF OF THE OPEN CLUSTER NGC 7142

作者：Sandquist Eric L^*; Shetrone Matthew; Serio Andrew W; Orosz Jerome

来源：Astronomical Journal, 2013, 146(2): 40.

DOI：10.1088/0004-6256/146/2/40

• binaries: eclipsing
• binaries: spectroscopic
• open clusters and associations: individual (NGC 7142)
• stars: distances
• stars: evolution

We analyze extensive BVRC I-C photometry and radial velocity measurements for three double-lined deeply eclipsing binary stars in the field of the old open cluster NGC 7142. The short period (P = 1.9096825 days) detached binary V375 Cep is a high probability cluster member, and has a total eclipse of the secondary star. The characteristics of the primary star (M = 1.288 +/- 0.017 M-circle dot) at the cluster turnoff indicate an age of 3.6 Gyr (with a random uncertainty of 0.25 Gyr), consistent with earlier analysis of the color-magnitude diagram. The secondary star (M = 0.871 +/- 0.008 M-circle dot) is not expected to have evolved significantly, but its radius is more than 10% larger than predicted by models. Because this binary system has a known age, it is useful for testing the idea that radius inflation can occur in short period binaries for stars with significant convective envelopes due to the inhibition of energy transport by magnetic fields. The brighter star in the binary also produces a precision estimate of the distance modulus, independent of reddening estimates: (m - M)(V) = 12.86 +/- 0.07. The other two eclipsing binary systems are not cluster members, although one of the systems (V2) could only be conclusively ruled out as a present or former member once the stellar characteristics were determined. That binary is within 0.degrees 5 of edge-on, is in a fairly long-period eccentric binary, and contains two almost indistinguishable stars. The other binary (V1) has a small but nonzero eccentricity (e = 0.038) in spite of having an orbital period under 5 days.

• 出版日期2013-8