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Astron. Astrophys. 324, L33-L36 (1997)
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Letter to the Editor
Hipparcos data on Herbig Ae/Be stars: an evolutionary scenario *
M.E. van den Ancker 1,
P.S. Thé 1,
H.R.E. Tjin A Djie 1,
C. Catala 2,
D. de Winter 3,
P.F.C. Blondel 1 and
L.B.F.M. Waters 1, 4
1 Astronomical Institute "Anton Pannekoek", University of
Amsterdam, Kruislaan 403, NL-1098 SJ Amsterdam, The Netherlands
2 Laboratoire d'Astrophysique et Unité de Recherche
associée au CNRS 285, Observatoire Midi-Pyrenées,
France
3 Dpto. Física Téorica C-XI, Facultad de
Ciencias, Universidad Autónoma de Madrid, Cantoblanco, E-28049
Madrid, Spain
4 SRON Space Research Laboratory, P.O. Box 800, 9700 AV
Groningen, The Netherlands
Received 24 April 1997 / Accepted 30 May 1997
Abstract
Fundamental astrophysical parameters (distance, temperature, luminosity, mass, age) of a sample of 10 Herbig Ae/Be candidates and 3 non-emission line A and B stars in star forming regions were computed combining Hipparcos parallaxes with data from literature. All genuine Herbig stars in our sample are located between the birthline and the zero-age main sequence (ZAMS) in the Hertzsprung-Russell diagram (HRD), in accordance with what is expected for pre-main sequence stars. The region in the HRD close to the birthline is relatively devoid of stars when compared to the region closer to the ZAMS, in agreement with the expected evolutionary time scales. The Herbig Ae/Be stars not associated with star forming regions were found to be located close to the ZAMS. Additionally we discuss a possible evolutionary scenario for the circumstellar environment of Herbig stars.
Key words: Circumstellar
matter 
Stars:
Distances
HR diagram
Stars: Pre-main
sequence
Stars: Variables
* Based on data from the Hipparcos astrometry satellite.
Send offprint requests to: M.E. van den Ancker (mario@astro.uva.nl)
© European Southern Observatory (ESO) 1997
Online publication: May 26, 1998
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