[Previous] | [Session 65] | [Next]
G. R. Knapp (Princeton University)
The Sloan Digital Sky Survey (SDSS) imaging data have proven to be a rich source of candidate very red, low-luminosity stars and brown dwarfs. SDSS detects early M dwarfs to about 1.5 kpc, late M and L dwarfs to about 100 pc and T (methane) dwarfs to 20-30 pc. The distribution of M star colors and magnitudes can be used to trace the vertical structure of the disk. The SDSS spectroscopic survey, which incorporates many stellar objects, produces a wealth of data supporting studies of chromospheric activity in M dwarfs, the properties of metal-poor M subdwarfs, and the incidence and properties of M dwarf/white dwarf binaries. Due to its i and z filters, SDSS can detect extremely red objects in an unbiased manner, and identify the complete range of spectral types from M to late T. A unified spectral sequence from M0 to T9 has been established using optical and near-infrared spectra, the latter mostly from UKIRT. Spectra and near infrared photometry trace the appearance (from late M through mid-L) of photospheric dust and its disappearance to later types and into the T sequence. Effective temperatures of 2200-1300 for early to late L, and 1300-800 for early to late T dwarfs are found. A space density of about one per 160 \rm pc-3 is found for T dwarfs, with an implied fraction of about 10% of the ``stellar'' mass in substellar objects in the solar neighborhood.
Funding for the SDSS is provided by the Alfred P. Sloan Foundation, NASA, NSF, DoE, Monbukagakusho, the Max Planck Society and the member institutions. The SDSS web site is http://www.sdss.org/.
[Previous] | [Session 65] | [Next]
Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.