A&A Supplement series, Vol. 123, May II 1997, 135-146

Received June 12; accepted September 12, 1996

Spectral classifications in the near infrared of stars with composite spectra

II. Study of a sample of 180 stars

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

Abstract:

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

 
• 1. Introduction
• 2. Observations, treatment of spectra and measure of equivalent widths
• 3. Composition of the sample
• 4. Spectral types and luminosity classes of the cooler components
• 5. Conclusions
• References