A&A Supplement series, Vol. 123, May II 1997, 135-146
Received June 12; accepted September 12, 1996
N. Ginestet, J.M. Carquillat, C. Jaschek, and M. Jaschek
Send offprint request: J.M. Carquillat
Observatoire Midi-Pyrénées, UMR No. 5572 (CNRS), 14 Avenue Edouard Belin, 31400 Toulouse, France
Observatoire de Strasbourg, URA 1280 (CNRS), 11 Rue de l'Université, 67000 Strasbourg, France
A sample of 180 supposedly composite-spectrum stars has been studied on the basis of spectra obtained in the near infrared (8370-8780 Å) at a dispersion of 33 Å/mm. The objective was to study the cooler components of the systems. Of our sample, 120 are true composite spectra, 35 are hot spectra of types B, F and 25 are Am stars. We find a strong concentration of the cooler components of the composite spectra around G8III. In view of the difficulty of classifying composite spectra, because of the superposition of an early type dwarf and a late type giant or supergiant spectrum, we have made several tests to control the classification based upon the infrared region. Since all tests gave positive results, we conclude that our classifications can be considered as being both reliable and homogeneous.
keywords: stars: classification -- infrared: stars -- binaries: spectroscopic