New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence

  title={New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence},
  author={John E. Gizis and David G. Monet and I. Neill Reid and J. Davy Kirkpatrick and James William Liebert and Rik J. Williams},
  journal={The Astronomical Journal},
  pages={1085 - 1099}
We have combined 2MASS and POSS II data in a search for nearby ultracool (later than M6.5) dwarfs with Ks < 12. Spectroscopic follow-up observations identify 53 M7–M9.5 dwarfs and seven L dwarfs. The observed space density is 0.0045 ± 0.0008 M8–M9.5 dwarfs per cubic parsec, without accounting for biases, consistent with a mass function that is smooth across the stellar/substellar limit. We show the observed frequency of Hα emission peaks at ∼100% for M7 dwarfs and then decreases for cooler… 
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