Astron. Astrophys. Suppl. Ser. 142, 389-398

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

V.I. Kuznetsov ¹ - G.Z. Boutenko ¹ - G.A. Lazorenko ² - P.F. Lazorenko ²

Send offprint request: V.I. Kuznetsov

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

Received May 28; accepted November 29, 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 V=14 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.

Key words: methods: numerical -- stars: fundamental parameters -- ISM: dust, extinction --Galaxy: open clusters and associations: individual: NGC 2244; NGC 2264