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A Cross-match of 2MASS and SDSS. II. Peculiar L Dwarfs, Unresolved Binaries, and the Space Density of T Dwarf Secondaries

Geiβler, Kerstin and Metchev, Stanimir and Kirkpatrick, J. Davy and Berriman, G. Bruce and Looper, Dagny (2011) A Cross-match of 2MASS and SDSS. II. Peculiar L Dwarfs, Unresolved Binaries, and the Space Density of T Dwarf Secondaries. Astrophysical Journal, 732 (1). Art. No. 56. ISSN 0004-637X.

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We present the completion of a program to cross-correlate the Sloan Digital Sky Survey Data Release 1 (SDSS DR1) and Two-Micron All-Sky Survey (2MASS) Point Source Catalog in search for extremely red L and T dwarfs. The program was initiated by Metchev and collaborators, who presented the findings on all newly identified T dwarfs in SDSS DR1 and estimated the space density of isolated T0-T8 dwarfs in the solar neighborhood. In the current work, we present most of the L dwarf discoveries. Our red-sensitive (z – J ≥ 2.75 mag) cross-match proves to be efficient in detecting peculiarly red L dwarfs, adding two new ones, including one of the reddest known L dwarfs. Our search also nets a new peculiarly blue L7 dwarf and, surprisingly, two M8 dwarfs. We further broaden our analysis to detect unresolved binary L or T dwarfs through spectral template fitting to all L and T dwarfs presented here and in the earlier work by Metchev and collaborators. We identify nine probable binaries, six of which are new and eight harbor likely T dwarf secondaries. We combine this result with current knowledge of the mass ratio distribution and frequency of substellar companions to estimate an overall space density of 0.005-0.05 pc^(–3) for individual T0-T8 dwarfs.

Item Type:Article
Related URLs:
URLURL TypeDescription
Metchev, Stanimir0000-0003-3050-8203
Kirkpatrick, J. Davy0000-0003-4269-260X
Berriman, G. Bruce0000-0001-8388-534X
Additional Information:© 2011 American Astronomical Society. Received 2010 September 10; accepted 2011 March 2; published 2011 April 14. This research has benefitted from the M, L, and T dwarf compendium housed at and maintained by Chris Gelino, Davy Kirkpatrick, and Adam Burgasser. This research has benefitted from the SpeX Prism Spectral Libraries, maintained by Adam Burgasser at This research has benefitted from the Ultracool Dwarf Catalog housed at This research has made use of data obtained from or software provided by the US National Virtual Observatory, which is sponsored by the National Science Foundation. Facilities: IRTF (SpeX)
Group:Infrared Processing and Analysis Center (IPAC)
Subject Keywords:brown dwarfs; stars: individual (2MASS J17373467+5953434, 2MASS J15423630-0045452, 2MASS J09175418+60280); stars: peculiar; surveys
Issue or Number:1
Classification Code:PACS: 95.80.+p; 97.80.-d; 97.10.Ri; 97.10.Nf; 97.20.Vs
Record Number:CaltechAUTHORS:20110503-152040272
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23538
Deposited By: Jason Perez
Deposited On:03 May 2011 22:43
Last Modified:28 Oct 2019 21:27

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