Discoveries from a Near-infrared Proper Motion Survey using Multi-epoch 2MASS Data

TL;DR

This study conducted a large near-infrared proper motion survey using 2MASS data, discovering numerous exotic objects like brown dwarfs and subdwarfs, and establishing standards for near-infrared classification, highlighting future research prospects.

Contribution

First large-scale near-infrared proper motion survey using 2MASS data, discovering new exotic objects and establishing spectroscopic standards for classification.

Findings

Discovered 2778 proper motion candidates, including 647 new objects.

Identified various exotic objects such as brown dwarfs and subdwarfs.

Refined definitions of exotic classes and analyzed their kinematics.

Abstract

We have conducted a 4030-square-deg near-infrared proper motion survey using multi-epoch data from the Two Micron All-Sky Survey (2MASS). We find 2778 proper motion candidates, 647 of which are not listed in SIMBAD. After comparison to DSS images, we find that 107 of our proper motion candidates lack counterparts at B-, R-, and I-bands and are thus 2MASS-only detections. We present results of spectroscopic follow-up of 188 targets that include the infrared-only sources along with selected optical-counterpart sources with faint reduced proper motions or interesting colors. We also establish a set of near-infrared spectroscopic standards with which to anchor near-infrared classifications for our objects. Among the discoveries are six young field brown dwarfs, five "red L" dwarfs, three L-type subdwarfs, twelve M-type subdwarfs, eight "blue L" dwarfs, and several T dwarfs. We further refine the definitions of these exotic classes to aid future identification of similar objects. We examine their kinematics and find that both the "blue L" and "red L" dwarfs appear to be drawn from a relatively old population. This survey provides a glimpse of the kinds of research that will be possible through time-domain infrared projects such as the UKIDSS Large Area Survey, various VISTA surveys, and WISE, and also through z- or y-band enabled, multi-epoch surveys such as Pan-STARRS and LSST.