A Candidate Wide Brown Dwarf Binary in the Argus Association: 2MASS J14504216-7841413 and 2MASS J14504113-7841383

TL;DR

This paper reports the discovery of a wide binary brown dwarf candidate in the Argus Association, identified through imaging and spectroscopy, with high membership probability and implications for low-mass binary formation.

Contribution

It presents the first identification of a candidate wide brown dwarf binary in the Argus Association using combined imaging, astrometry, and spectroscopy.

Findings

Binary separated by 4.23 arcseconds with common proper motion.

Spectral types M8pec and M9pec indicating low gravity features.

Estimated mass of each component is about 0.04 solar masses.

Abstract

[not part of Research Note] We report the discovery of a widely-separated low-mass binary as a candidate member of the $\sim$40 Myr Argus Association. Resolved imaging and astrometry with 2MASS and LDSS-3 reveal a common proper motion pair of red sources separated by 4.23''$\pm$0.11'', with the secondary roughly one magnitude fainter at $i$, $z$ and $J$. Resolved spectroscopy indicates component types of M8pec and M9pec, the peculiarities arising from weak Na I and strong VO absorption characteristic of low gravity sources. With its small proper motion and estimated 75$\pm$25 pc distance, the BANYAN II tool indicates a membership probability of 93% in Argus, which would be consistent with a pair of brown dwarfs of mass $\sim$0.04 M$_{\odot}$ separated by $\sim$300 AU.