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| Paper: |
New Surveys for Brown Dwarfs and Their Impact on the IMF |
| Volume: |
448, 16th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun |
| Page: |
323 |
| Authors: |
Kirkpatrick, J. D. |
| Abstract: |
Although first predicted to exist in the early 1960s, brown dwarfs were not
discovered in bulk until decades later by deep, large-area, infrared-capable surveys such
as 2MASS, SDSS, and DENIS. Hundreds of examples are now known, enabling the
study of brown dwarfs as a population in their own right. Despite these successes,
only the warmest brown dwarfs have so far been identified. The coolest brown
dwarfs currently known are field late-T dwarfs with Teff≈500–600K and
implied masses of around 5-35 MJup for assumed ages of 1-10 Gyr. Foremost is the
question of what cooler objects will look like spectroscopically and whether a new
spectral class beyond T, dubbed “Y”, will be needed. These cooler field brown
dwarfs must exist, as studies of young star formation regions have revealed objects
even lower in mass, which, at the age of the field population, will have cooled to
temperatures well below 500K. Finding and characterizing such cold objects will set
important boundary conditions on the shape of the initial mass function at the lowest masses and
determine what the low-mass cut-off for star formation is. Here I highlight
discoveries from the latest generation of brown dwarf surveys – UKIDSS, CFBDS,
and the recently launched WISE – and discuss their impact on our understanding
of the field mass function at very low masses. |
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