Discovery of the Widest Very Low Mass Field Binary

TL;DR

This paper reports the discovery of the widest very low mass binary system in the field, with a separation of about 6700 AU, confirmed through proper motion measurements and spectral analysis.

Contribution

It presents the identification and confirmation of the widest very low mass binary, providing new data to inform formation models of such systems.

Findings

Confirmed common proper motion with 99.5% probability

Spectral types of M6 and M7 for the components

Component masses of approximately 0.105 and 0.091 solar masses

Abstract

We present the discovery of the widest (~6700 AU) very low mass field binary to date, found in a proper motion cross-match of the Sloan Digital Sky Survey and the Two Micron All Sky Survey. Our follow-up J-band imaging provides a 10-year baseline for measuring proper motions. Consequently, we are able to confirm the common proper motion of the pair to within 10 mas, implying a 99.5% probability of their physical association. Near infrared spectra of the components indicate spectral types of M6+/-1 and M7+/-1. The system resides at a spectroscopic distance of 105+/-13 pc and has an angular separation of 63.38+/-0.05 arcsec. We have used evolutionary models to infer component masses of 0.105^{+0.029}_{-0.017} M_sun and 0.091^{+0.010}_{-0.007} Msun. The large separation and low binding energy of this system can provide constraints for formation models of very low mass stars.