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Astron. Astrophys. 336, 953-959 (1998)
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The HR-diagram from Hipparcos data. Absolute magnitudes and kinematics of Bp - Ap stars *
A.E. Gómez 1,
X. Luri 1, 2,
S. Grenier 1,
F. Figueras 2,
P. North 3,
F. Royer 1,
J. Torra 2 and
M.O. Mennessier 4
1 Observatoire de Paris-Meudon, D.A.S.G.A.L., URA 335 du
CNRS, F-92195 Meudon Cedex, France
2 Departament d'Astronomia i Meteorologia, Universitat de
Barcelona, Avda. Diagonal 647, E-08028, Barcelona, Spain
3 Institut d'Astronomie de l'Université de Lausanne,
CH-1290 Chavannes des Bois, Switzerland
4 Université Montpellier II, Groupe de Recherche en
Astronomie et Astrophysique du Languedoc, URA 1368 du CNRS, F-34095
Montpellier Cedex 5, France
Received 22 January 1997 / Accepted 6 May 1998
Abstract
The HR-diagram of about 1000 Bp - Ap stars in the solar neighbourhood has been constructed using astrometric data from Hipparcos satellite as well as photometric and radial velocity data. The LM method (Luri, 1995; Luri, Mennessier et al., 1996) allows the use of proper motion and radial velocity data in addition to the trigonometric parallaxes to obtain luminosity calibrations and improved distances estimates.
Six types of Bp - Ap stars have been examined: He-rich, He-weak, HgMn, Si, Si+ and SrCrEu. Most Bp - Ap stars lie on the main sequence occupying the whole width of it (about 2 mag), just like normal stars in the same range of spectral types. Their kinematic behaviour is typical of thin disk stars younger than about 1 Gyr.
A few stars found to be high above the galactic plane or to have a high velocity are briefly discussed.
Key words: stars: chemically
peculiar 
stars:
distances
stars: fundamental
parameters
stars: Hertzsprung-Russell (HR)
diagram
stars: kinematics
* Based on data from the ESA Hipparcos astrometry satellite and photometric data collected in the Geneva system at ESO, La Silla (Chile) and at Jungfraujoch and Gornergrat Observatories (Switzerland). Tables 3 and 4 are only available in electronic form at the CDS via
anonymous ftp to cdsarc.u-strasbg.fr/pub/cats/J/A+A/336/953 or
via http://cdsweb.u-strasbg.fr/Abstract.html
Send offprint requests to: A.E. Gómez
© European Southern Observatory (ESO) 1998
Online publication: July 27, 1998
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