The missing M dwarfs

Abstract

We present evidence which indicates the luminosity functions of star forming regions, open star clusters and the field dips between spectral types M7-M8. We attribute this to a sharp local drop in the luminosity-mass relation and speculate that this is caused by the beginning of dust formation in the atmospheres of objects in this effective temperature regime. This effect is not predicted by the current generation of low mass stellar/substellar evolutionary models. If our interpretation is correct then this result has important implications for investigations concerned with the mass functions of star forming regions and young open star clusters. For example, it suggests that some brown dwarfs have higher masses than previously thought.

5 pages, 4 figures, accepted for publication in MNRAS (letters)

References in corpus (7)

• The Limiting Effects of Dust in Brown Dwarf Model Atmospheres
• Evolutionary models for low-mass stars and brown dwarfs: uncertainties and limits at very young ages
• The Luminosity & Mass Function of the Trapezium Cluster: From B stars to the Deuterium Burning Limit
• Clouds and Chemistry: Ultracool Dwarf Atmospheric Properties from Optical and Infrared Colors
• Infrared Spectroscopy of Substellar Objects in Orion
• The Substellar Mass Function in sigma Orionis
• Meeting the Cool Neighbours I: Nearby stars in the NLTT Catalogue - Defining the sample

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