Discovery And Characterization of Wide Binary Systems With a Very Low Mass Component

TL;DR

This study reports the discovery and characterization of 23 wide binary systems with low-mass components, including brown dwarfs, using proper motion surveys and follow-up spectroscopy, revealing new systems and statistical evidence of their physical association.

Contribution

It presents the discovery of 23 wide low-mass binary systems, including a previously unknown brown dwarf companion, and provides statistical validation of their physical binary nature.

Findings

Discovered 14 new low-mass binary systems with separations >250 AU.

Identified a brown dwarf companion at 340 AU, previously unknown.

14 systems have a mass ratio below 0.3.

Abstract

We report the discovery of 14 low-mass binary systems containing mid-M to mid-L dwarf companions with separations larger than 250 AU. We also report the independent discovery of 9 other systems with similar characteristics that were recently discovered in other studies. We have identified these systems by searching for common proper motion sources in the vicinity of known high proper motion stars, based on a cross-correlation of wide area near-infrared surveys (2MASS, SDSS, and SIMP). An astrometric follow-up, for common proper motion confirmation, was made with SIMON and/or CPAPIR at the OMM 1.6 m and CTIO 1.5 m telescopes for all the candidates identified. A spectroscopic follow-up was also made with GMOS or GNIRS at Gemini to determine the spectral types of 11 of our newly identified companions and 10 of our primaries. Statistical arguments are provided to show that all of the systems we report here are very likely to be physical binaries. One of the new systems reported features a brown dwarf companion: LSPM J1259+1001 (M5) has an L4.5 (2M1259+1001) companion at about 340 AU. This brown dwarf was previously unknown. Seven other systems have a companion of spectral type L0-L1 at a separation in the 250-7500 AU range. Our sample includes 14 systems with a mass ratio below 0.3.