The Galactic Disk Mass Budget. II. Brown Dwarf Mass Function and Density

The Galactic disk mass - budget : II . Brown

In this paper, we extend the calculations conducted previously in the stellar regime (Chabrier, 2001) to determine the brown dwarf initial mass function in the Galactic disk. We perform Monte Carlo calculations taking into account the brown dwarf formation rate, spatial distribution and binary fraction. Comparison with existing surveys seems to exclude a power-law mass function as steep as the ...

The Galactic disk mass-budget : I. stellar mass-function and density

In this paper, we use the general theory worked out within the past few years for the structure and the evolution of low-mass stars to derive the stellar mass-function in the Galactic disk down to the vicinity of the hydrogen-burning limit, from the observed nearby luminosity functions. The accuracy of the mass-magnitude relationships derived from the afore-mentioned theory is examined by compa...

Vertical distribution of Galactic disk stars : ⋆ II . The surface mass density in the Galactic plane

High resolution spectra data of red clump stars towards the NGP have been obtained with the high resolution spectrograph Elodie at OHP for Tycho-2 selected stars. Combined with Hipparcos local analogues, we determine both the gravitational force law perpendicular to the Galactic plane, and the total surface mass density and thickness of the Galactic disk. The surface mass density of the Galacti...

The Brown Dwarf Mass Function from Pixel Microlensing

We argue that gravitational microlensing is a feasible technique for measuring the mass function of brown dwarf stars in distant galaxies. Microlensing surveys of the bulge of M31, and of M87 in the Virgo cluster, may provide enough events to differentiate the behaviour of the mass function of lenses below the hydrogen burning limit (though we find that M87 is a more favourable target). Such ob...

Synthetic Spectra and Mass Determination of the Brown Dwarf Gl229B