Issue |
A&A
Volume 403, Number 3, June I 2003
|
|
---|---|---|
Page(s) | 993 - 1002 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20030429 | |
Published online | 23 May 2003 |
Reprocessing the Hipparcos data of evolved stars*,**
III. Revised Hipparcos period–luminosity relationship for galactic long-period variable stars
1
Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
2
Institut d'Astronomie et d'Astrophysique, Université Libre de Bruxelles, CP 226, Boulevard du Triomphe, 1050 Bruxelles, Belgium e-mail: pourbaix; ajorisse@astro.ulb.ac.be
3
Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA e-mail: imants@pha.jhu.edu
Corresponding author: G. R. Knapp, gk@astro.princeton.edu
Received:
29
January
2003
Accepted:
21
March
2003
We analyze the K band luminosities of a sample of galactic
long-period variables using
parallaxes measured by the Hipparcos mission. The parallaxes are in most
cases re-computed from the Hipparcos Intermediate Astrometric Data
using improved astrometric fits and chromaticity corrections. The K band
magnitudes are taken from the literature and from measurements by COBE,
and are corrected for interstellar and circumstellar extinction.
The sample contains stars of several spectral types: M, S and C, and of several
variability classes: Mira, semiregular SRa, and SRb. We find that the
distribution of stars in the period–luminosity plane is independent of
circumstellar chemistry, but that the different variability types have
different P–L distributions. Both the Mira variables and the
SRb variables have reasonably well-defined period–luminosity relationships,
but with very different slopes.
The SRa variables are distributed between the two classes, suggesting that they
are a mixture of Miras and SRb, rather than a separate class of stars.
New period–luminosity relationships are derived based on our revised Hipparcos parallaxes. The Miras show a similar period–luminosity
relationship to that found for Large Magellanic Cloud Miras by
Feast et al. (1989).
The maximum absolute K magnitude of the sample is about -8.2 for both Miras
and semi-regular stars, only slightly fainter than the expected AGB limit. We
show that the stars with the longest periods ( d) have high
mass loss rates and are almost all Mira variables.
Key words: stars: carbon / stars: AGB and post-AGB / stars: oscillations
© ESO, 2003
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