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The Missing M Dwarfs

Published online by Cambridge University Press:  26 May 2016

Richard F. Jameson ,
Paul D. Dobbie ,
David J. Pinfield  and
Simon T. Hodgkin
Richard F. Jameson
Affiliation:
Dept. of Physics & Astronomy, University of Leicester, Leicester, UK.
Paul D. Dobbie
Affiliation:
Dept. of Physics & Astronomy, University of Leicester, Leicester, UK.
David J. Pinfield
Affiliation:
Astrophysics Research Institute, Liverpool John Moores University, Birkenhead, UK
Simon T. Hodgkin
Affiliation:
Institute of Astronomy, University of Cambridge, Cambridge, UK

Abstract

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We present evidence for a drop in the luminosity function around spectral type M7–M8. This shows in both field stars and the clusters σ–Orionis, the Trapezium, IC 348, IC 2391, α–Perseii, the Pleiades and, possibly, the globular cluster M4. This can be explained by a sudden drop in the luminosity-mass relation. Theoretical models, which include dust, do not show this effect, although they predict dust forming at about spectral type M7. We suggest that this drop in the luminosity-mass relation could be modelled by considering larger size dust grains. The drop in the luminosity-mass relation suggests that star/brown dwarf masses below M7–M8 will be larger than predicted by current models.

Type
Part 4. Observations of Young Brown Dwarfs (age ≃ 50–200 Myr)
Information
Symposium - International Astronomical Union , Volume 211: Brown Dwarfs , 2003 , pp. 171 - 174
Copyright
Copyright © Astronomical Society of the Pacific 2001 

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