L Dwarfs Found in Sloan Digital Sky Survey Commissioning Imaging Data

Abstract

This paper describes the discovery of seven dwarf objects of spectral type `L' (objects cooler than the latest M dwarfs) in commissioning imaging data taken by the Sloan Digital Sky Survey (SDSS). Low-resolution spectroscopy shows that these objects have spectral types from L0 to L8. Comparison of the SDSS and 2MASS photometry for several of these objects indicates the presence of significant opacity at optical wavelengths, perhaps due to atmospheric dust. This comparison also demonstrates the high astrometric accuracy (better than 1'' for these faint sources) of both surveys. The L dwarfs are shown to occupy a distinctive region of color-color space as measured in the SDSS filters, which should enable their identification in a straightforward way. This should lead eventually to a complete sample of many hundreds of these low mass objects, or about one per 15 square degrees to i'~20, in the complete SDSS data set.Comment: 22 Pages Latex with embedded figures, submitted to AJ. Also available at http://www.astro.princeton.edu/~strauss/sdss/ldwarf.ps (with high-resolution figures

L-Dwarf Binaries in the 20-Parsec Sample

“…; D02: Trigonometric parallax fromDahn et al (2002); Hip: Trigonometric parallax from Hipparcos (ESA, 1997); T95: Trigonometric parallax fromTinney et al (1995); V04: Trigonometric parallax fromVrba et al (2004).References. (1) Irwin et al (1991); (2) Gizis et al (2000); (3) Reid et al, in preparation (Paper X); (4) Cruz et al (2003) (Paper V); (5) Martín et al (1999); (6) Cruz et al (2007) (Paper IX); (7) Hawley et al (2002); (8) Geballe et al (2002); (9) Chiu et al (2006); (10) Delfosse et al (1997); (11) Gizis (2002); (12) Kendall et al (2004); (13) Kirkpatrick et al (1999); (14) Kirkpatrick et al (2000); (15) Kirkpatrick et al (2001); (16)Fan et al (2000). Notes on individual stars.…”

Meeting the Cool Neighbors. X. Ultracool Dwarfs From the 2mass All-Sky Data Release

“…Results from those surveys, and from the deep optical imaging of the Sloan Digital Sky Survey (SDSS; York et al 2000), have revolutionized our understanding of the very low-mass dwarfs that populate the lower reaches of the H-R diagram. Although predated by the identification of the first incontrovertible brown dwarf (Nakajima et al 1995), the avalanche of discoveries over the past decade (Delfosse et al 1997;Kirkpatrick et al 1999Kirkpatrick et al , 2000Fan et al 2000;Hawley et al 2002) would not have been possible without the unparalleled sensitivity provided by those surveys. Initial investigations operated in discovery mode, pushing detection to lower and lower temperatures, and extending the spectral classification system to types L (K99; Martín et al 1999) and T (Geballe et al 2002;Burgasser et al 2002Burgasser et al , 2006.…”

Large-Scale Searches for Brown Dwarfs and Free-Floating Planets

“…Brown dwarfs were discovered within the SDSS photometric catalogues from the outset, with seven L dwarfs and two T dwarfs identified in commissioning data (Strauss et al 1999;Tsvetanov et al 2000;Fan et al 2000). Candidates were selected via (i − z ) vs (r − i ) colour-colour diagrams, and via r and i band dropout searches.…”