Reprocessing the Hipparcos data of evolved stars. III. Revised Hipparcos period-luminosity relationship for galactic long-period variable stars
Abstract
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. (\cite{Feast-1989:a}). 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 (P>400 d) have high mass loss rates and are almost all Mira variables.
Based on observations from the Hipparcos astrometric satellite operated by the European Space Agency (ESA \cite{Hipparcos}). Table \ref{Tab:data1} is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/403/993- Publication:
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Astronomy and Astrophysics
- Pub Date:
- June 2003
- DOI:
- 10.1051/0004-6361:20030429
- arXiv:
- arXiv:astro-ph/0301579
- Bibcode:
- 2003A&A...403..993K
- Keywords:
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- stars: carbon;
- stars: AGB and post-AGB;
- stars: oscillations;
- Astrophysics
- E-Print:
- Comments welcome. Submitted to A&