The UKIDSS-2MASS Proper Motion Survey I: Ultracool dwarfs from UKIDSS DR4

TL;DR

This paper presents a new infrared proper motion survey combining UKIDSS and 2MASS data, identifying 267 low mass stars and brown dwarfs, including known and new candidates, and analyzing their proper motions.

Contribution

It introduces a combined infrared proper motion survey using UKIDSS and 2MASS data, discovering new ultracool dwarf candidates and analyzing proper motion accuracy.

Findings

Recovered all known L and T dwarfs above 2MASS detection limit.

Identified eight new L dwarf candidates and one in GCS.

Found potential underestimation of proper motions in GCS data.

Abstract

The UKIRT Infrared Deep Sky Survey (UKIDSS) is the first of a new generation of infrared surveys. Here we combine the data from two UKIDSS components, the Large Area Survey (LAS) and the Galactic Cluster Survey (GCS), with 2MASS data to produce an infrared proper motion survey for low mass stars and brown dwarfs. In total we detect 267 low mass stars and brown dwarfs with significant proper motions. We recover all ten known single L dwarfs and the one known T dwarf above the 2MASS detection limit in our LAS survey area and identify eight additional new candidate L dwarfs. We also find one new candidate L dwarf in our GCS sample. Our sample also contains objects from eleven potential common proper motion binaries. Finally we test our proper motions and find that while the LAS objects have proper motions consistent with absolute proper motions, the GCS stars may have proper motions which are significantly under-estimated. This is due possibly to the bulk motion of some of the local astrometric reference stars used in the proper motion determination.