Document Type

Article

Publication Date

7-27-2011

Abstract

Improved orbital elements for three double-lined spectroscopic binaries, 47 And, 38 Cas, and HR 8467, have been determined with extensive new radial velocities. For 38 Cas lines of the secondary have been detected for the first time. Given the orbital periods for these systems of 35.3682, 134.130, and 42.3813 days, respectively, it is not surprising that all three have either moderate or relatively high eccentricities. The orbital dimensions (a1sin i and a2sin i) and minimum masses (m1sin 3i and m2sin 3i) have accuracies of 0.5% or better. An astrometric orbit for 38 Cas, which was recomputed with Hipparcos astrometry and our new spectroscopic orbital elements, produces a very high orbital inclination of 88° ± 5°. We have found no evidence for eclipses in either 38 Cas or HR 8467. We estimate that both components of 38 Cas are slightly metal poor with [Fe/H] = −0.3. The two components of 47 And are Am main-sequence stars, while our spectral types for 38 Cas are F6 dwarf and G5 dwarf for its primary and secondary, respectively. For HR 8467 we determined spectral types of F6 subgiant and F6 dwarf for the components. The primary of HR 8467 is likely just beginning to traverse the Hertzsprung gap and is rotating more slowly than its pseudosynchronous velocity, while the main-sequence secondary is rotating pseudosynchronously. On the other hand, the binary components of 47 And and 38 Cas are rotating significantly faster than their pseudosynchronous velocities.

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