Astron. Astrophys. 364, 217-224 (2000)

Accurate masses of very low mass stars

IV. Improved mass-luminosity relations ^*

X. Delfosse ¹, T. Forveille ^2,3, D. Ségransan ³, J.-L. Beuzit ^3,2, S. Udry ⁴, C. Perrier ³ and M. Mayor <sup>4

1</sup> Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Canary Islands, Spain
² Canada-France-Hawaii Telescope Corporation, 65-1238 Mamaloha Highway, Kamuela, HI 96743, USA
³ Observatoire de Grenoble, 414 rue de la Piscine, Domaine Universitaire de St Martin d'Hères, 38041 Grenoble, France
⁴ Observatoire de Genève, 51 Ch des Maillettes, 1290 Sauverny, Switzerland

Received 21 July 2000 / Accepted 28 September 2000

Abstract

We present improved visual and near-infrared empirical mass-luminosity relations for very low mass stars (M0.6 ). These relations make use of all stellar masses in this range known with better than 10% accuracy, most of which are new determinations with 0.2 to 5% accuracy from our own programme, presented in a companion paper.

As predicted by stellar structure models, the metallicity dispersion of the field populations induces a large scatter around the mean V band relation, while the infrared relations are much tighter. The agreement of the observed infrared mass-luminosity relations with the theoretical relations of Baraffe et al. (1998) and Siess et al. (2000) is impressive, while we find an increasingly significant discrepancy in the V band for decreasing masses. The theoretical mass-luminosity relation which is insufficiently steep, and has introduced significant errors in the local stellar mass functions derived from V band luminosity functions.

Key words: stars: binaries: general stars: binaries: spectroscopic stars: binaries: visual stars: low-mass, brown dwarfs techniques: radial velocities stars: late-type

* Based on observations made at the Observatoire de Haute Provence (CNRS), and at the CFH Telescope, operated by the NRCC, the CNRS and the University of Hawaii

Send offprint requests to: Xavier Delfosse (delfosse@ll.iac.es)

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Contents

• 1. Introduction
• 2. Sample
  • 2.1. Accurate masses for M dwarfs
  • 2.2. Photometry
• 3. Visible and infrared mass/Luminosity relations
• 4. Comparison to theoretical models
• 5. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: December 15, 2000
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