Thirteen New M Dwarf + T Dwarf Pairs Identified with WISE/NEOWISE

TL;DR

This paper reports the discovery of 13 new M dwarf + T dwarf pairs using WISE/NEOWISE data, significantly increasing known systems and providing new benchmarks for studying substellar formation, evolution, and atmospheres.

Contribution

The study identifies 13 new widely separated M dwarf + T dwarf systems, expanding the sample by about 60% and offering prime targets for JWST to test formation and atmospheric models.

Findings

Increased known M+T systems by ~60%.

Discovery of wide T dwarf companions with separations up to 7100 au.

Identification of systems with potential for atmospheric and evolutionary studies.

Abstract

We present the discovery of 13 new widely separated T dwarf companions to M dwarf primaries, identified using WISE/NEOWISE data by the CatWISE and Backyard Worlds: Planet 9 projects. This sample represents a $\sim$60% increase in the number of known M+T systems, and allows us to probe the most extreme products of binary/planetary system formation, a discovery space made available by the CatWISE2020 catalog and the Backyard Worlds: Planet 9 effort. Highlights among the sample are WISEP J075108.79-763449.6, a previously known T9 thought to be old due to its SED, which we now find is part of a common-proper-motion pair with L 34-26 A, a well studied young M3 V star within 10 pc of the Sun; CWISE J054129.32-745021.5 B and 2MASS J05581644-4501559 B, two T8 dwarfs possibly associated with the very fast-rotating M4 V stars CWISE J054129.32-745021.5 A and 2MASS J05581644-4501559 A; and UCAC3 52-1038 B, which is among the widest late T companions to main sequence stars, with a projected separation of $\sim$7100 au. The new benchmarks presented here are prime $JWST$ targets, and can help us place strong constraints on formation and evolution theory of substellar objects as well as on atmospheric models for these cold exoplanet analogs.