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Astron. Astrophys. 330, 619-625 (1998)

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The absolute magnitude of the early type MK standards
from Hipparcos parallaxes *

C. Jaschek 1 and A.E. Gómez 2

1 Teso de la Feria 39, E-37008 Salamanca, Spain
2 Observatoire de Paris-Meudon, D.A.S.G.A.L., CNRS URA 335, F-92195 Meudon Cedex, France

Received 15 July 1997 / Accepted 22 September 1997


We analyse the standards of the MK system with the help of Hipparcos parallaxes, using only stars for which the error of the absolute magnitude is [FORMULA] 0.3 mag. We find that the main sequence is a wide band and that, although in general giants and dwarfs have different absolute magnitudes, the separation between luminosity classes V and III is not clear. Furthermore, there are a number of exceptions to the strict relation between luminosity class and absolute magnitude. We analyse similarly the system of standards defined by Garrison & Gray (1994) separating low and high rotational velocity standards. We find similar effects as in the original MK system.

We propose a revision of the MK standards, to eliminate the most deviant cases.

Key words: stars: early type MK standards – absolute magnitude

* Based on data from the ESA Hipparcos astrometry satellite

Send offprint requests to: A.E. Gómez

© European Southern Observatory (ESO) 1998

Online publication: January 16, 1998