New Light on Dark Stars

Part of the series Springer Praxis Books pp 237-288

Brown dwarfs

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6.10 Summary

The main conclusions of this chapter can be summarised as follows:
  • The existence of brown dwarfs has now been amply confirmed through direct observations.

  • Wide-angle near-infrared surveys (DENIS, 2MASS) and deep optical surveys (SDSS) are uncovering numerous examples of L- and T-type brown dwarfs in the general field.

  • Theoretical models are becoming increasingly mature. Dust and cloud formation play important roles in the evolution of the atmospheric properties of these cool dwarfs.

  • Brown dwarfs are relatively rare as companions to main sequence (or post main sequence) stars; approximately 15% of ultracool dwarfs are near equal-mass binaries with separations of 5–15 AU.

  • In the next few years, mid-infrared satellites, such as Spitzer, are likely to find brown dwarfs with temperatures as low as 300 K, almost certainly requiring the addition of a new spectral class, ammonia-rich Y dwarfs.