Spectral classification of O–M stars on the basis of UBV photometry

¹ International Centre for Astronomical, Medical and Ecological Investigations, National Academy of Sciencies of the Ukraine, Golosiiv, 252680 Kyiv-127, Ukraine e-mail: kouznets@mao.kiev.ua
² Main Astronomical Observatory, National Academy of Sciencies of the Ukraine, Golosiiv, 252680 Kyiv-127, Ukraine e-mail: gallaz@mao.kiev.ua

Send offprint request to: V.I. Kuznetsov

Received: 28 May 1999
Accepted: 29 November 1999

Abstract


A new technique allowing the Q-method to be used surely for both the spectral classification of young O–A0 stars and older spectral subclasses A1–M5 is described. Characteristics of interstellar light absorption dependence on distance in the given direction of the sky is used as a main criterion for excluding possible multiplicity of star spectral estimates at some constant values of Q_UBV. Information on open cluster membership probabilities is also useful as additional criterion of the spectral classification. The method was tested on stars up to mag in directions of young open clusters NGC 2244 and NGC 2264. The spectral study based on UBV photometry was extended to faint stars of NGC 2264 in the V magnitude range 17-22 mag.