Constraining the distribution of L and T dwarfs in the galaxy

R. E. Ryan, N. P. Hathi, S. H. Cohen, Rogier Windhorst

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


We estimate the thin-disk scale height of the Galactic population of L and T dwarfs based on star counts from 15 deep parallel fields from the Hubble Space Telescope. From these observations, we have identified 28 candidate L and T dwarfs based on their i′-z′ color and morphology. By comparing these star counts with a simple Galactic model, we estimate the scale height to be 350 ± 50 pc, which is consistent with the increase in vertical scale with decreasing stellar mass and is independent of reddening, color-magnitude limits, and other Galactic parameters. With this refined measure, we predict that less than 109 M of the Milky Way can be in the form of L and T dwarfs and confirm that high-latitude, z ≃6 galaxy surveys that use the i′-band dropout technique are 97%-100% free of L and T dwarf interlopers.

Original languageEnglish (US)
Pages (from-to)L159-L162
JournalAstrophysical Journal
Issue number2 II
StatePublished - Oct 1 2005

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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