Open AccessComposite spectra Paper 16: HR 3222, a 2.5‐yr binary with a metallic‐line secondary
Author(s) -
Griffin R. E. M.,
Griffin R. F.
Publication year - 2010
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2009.15800.x
Subject(s) - physics , astrophysics , radial velocity , spectral line , wavelength , binary number , stars , binary star , spectroscopy , eccentricity (behavior) , metal , line (geometry) , composite number , astronomy , optics , geometry , composite material , materials science , arithmetic , mathematics , metallurgy , law , political science
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.