An Infrared High Proper Motion Survey Using 2MASS and SDSS: Discovery of M, L and T Dwarfs

TL;DR

This study used 2MASS and SDSS data to discover 36 new high proper motion objects, including M, L, and T dwarfs, expanding knowledge of nearby ultracool dwarfs and their properties.

Contribution

The paper presents a new infrared survey method combining 2MASS and SDSS data that identified previously unknown high proper motion M, L, and T dwarfs.

Findings

Discovered 36 new high proper motion ultracool dwarfs.

Spectroscopic confirmation of spectral types from M8 to T4.

Several objects are within 100 parsecs, including a T dwarf at 25 parsecs.

Abstract

A search of the Two Micron All Sky Survey and Sloan Digital Sky Survey reveals 36 previously unknown high proper motion objects with J<17. Their red-optical colors indicate that 27 are M dwarfs, 8 are early-type L dwarfs, and 1 is a late-type T dwarf. The L dwarfs have J-Ks colors near the extrema of known L dwarfs indicating that previous surveys for L dwarfs using color as a selection criterion may be biased. Followup near-infrared spectroscopy of 6 dwarfs confirm they are all late-type with spectral types ranging from M8 to T4. Spectroscopy also shows that some of the L dwarf spectra exhibit peculiar features similar to other peculiar "blue" L dwarfs which may indicate that these dwarfs have a relatively condensate free atmosphere or may be metal poor. Photometric distance estimates indicate that 22 of the new M, L and T dwarfs lie within 100 pc of the Sun with the newly discovered T dwarf, 2MASS J10595185+3042059, located at about 25 pc. Based on the colors and proper motions of the newly identified objects, several appear to be good subdwarf candidates. The proper motions of known ultracool dwarfs detected in our survey were also measured, including, for the first time, SDSS J085834.42+325627.6 (T1), SDSS J125011.65+392553.9 (T4) and 2MASS J15261405+2043414 (L7).