Binary nature and elemental abundances of 2 Lyn and HD 169981

Abstract

Abstract. We analyse high-resolution spectrograms of the early A-type stars HD 169981 and 2 Lyn. For the spectroscopic and photometric binary HD 169981 we determine the abundances of certain chemical elements. The derived atmospheric parameters show the star to be an A giant. The abundances of the elements Mg, Si, Ti, Cr, and Fe are very close to solar, only C and O show slight underabundances. 2 Lyn has been primarily studied for the occurrence of radial velocity variations. The star is probably a spectroscopic binary with a period of about 3.6 years. Preliminary orbital elements are derived. The search for shorter radial velocity variations gives hints of periods of 69.2, 1.56 and 1.53 days. Both of the last-mentioned periods are in the order of the expected rotation period of the star. The stellar parameters are estimated and for certain elements we determined the abundances.

A Search for Short-Term RV Variations in Early-Type Binaries

“…In the case of 21 Her a very careful disentangling of orbital and additional RV variations was necessary. Including our own and older observations of Harper (1934), the final solution allowed us to derive also a slight but significant increase of the orbital period with a rate of 0.34 secy -1 (Lehmann et al, 2001c).…”