Journal Article

Composite spectra Paper 16: HR 3222, a 2.5-yr binary with a metallic-line secondary

R. E. M. Griffin and R. F. Griffin

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 402, issue 3, pages 1675-1684
Published in print March 2010 | ISSN: 0035-8711
Published online February 2010 | e-ISSN: 1365-2966 | DOI:
Composite spectra Paper 16: HR 3222, a 2.5-yr binary with a metallic-line secondary

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HR 3222 is a late-type giant star that has long been known as a spectroscopic binary. A single-lined orbit is readily found; it has a period of 955 d and an eccentricity of 0.33. The spectrum is noticeably composite, especially at short wavelengths; radial-velocity traces show a weak secondary dip that is broadened by a rotational velocity of 18 km s−1. We employ high-dispersion spectroscopy and uncover the secondary spectrum by subtracting from the observed composite one the spectrum of the K0 giant β Gem; the residue is a metallic-line star of type kA8hF2mF4, and measurements of its wavelength displacement from the primary spectrum give a more reliable radial velocity for that component than seems achievable from radial-velocity traces. The mass ratio is 1.20 ± 0.03. The stars can both be placed on an evolutionary track corresponding to an age of 1.4 Gyr. The fact that the secondary component is a metallic-line star cannot be attributed to the result of tidal effects in this binary system.

Keywords: binaries: spectroscopic; stars: individual: HR 3222

Journal Article.  6748 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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