New M, L, and T Dwarf Companions to Nearby Stars from the Wide-field Infrared Survey Explorer

TL;DR

This paper reports the discovery and confirmation of 11 late-type dwarf companions to nearby stars using WISE and 2MASS data, including new and previously known objects, with spectral analysis providing insights into their properties.

Contribution

The study identifies 11 candidate late-type companions, confirming eight through proper motion analysis and providing spectral classifications, including new discoveries and characterization of peculiar L dwarfs.

Findings

Eight companions confirmed via proper motion

Discovery of new T8 and L5 dwarf companions

Spectral analysis suggests diverse properties and metallicity levels

Abstract

We present 11 candidate late-type companions to nearby stars identified with data from the Wide-field Infrared Survey Explorer (WISE) and the Two Micron All-Sky Survey (2MASS). Eight of the candidates are likely to be companions based on their common proper motions with the primaries. The remaining three objects are rejected as companions, one of which is a free-floating T7 dwarf. Spectral types are available for five of the companions, which consist of M2V, M8.5V, L5, T8, and T8. Based on their photometry, the unclassified companions are probably two mid-M dwarfs and one late-M/early-L dwarf. One of the T8 companions, WISE J142320.84+011638.0, has already been reported by Pinfield and coworkers. The other T8 companion, ULAS J095047.28+011734.3, was discovered by Burningham and coworkers through the United Kingdom Infrared Telescope Infrared Deep Sky Survey, but its companionship has not been previously recognized in the literature. The L5 companion, 2MASS J17430860+8526594, is a new member of a class of L dwarfs that exhibit unusually blue near-IR colors. Among the possible mechanisms that have been previously proposed for the peculiar colors of these L dwarfs, low metallicity does not appear to be a viable explanation for 2MASS J17430860+8526594 since our spectrum of the primary suggests that its metallicity is not significantly subsolar.