Two new ultra-cool benchmark systems from WISE+2MASS

TL;DR

This paper reports the discovery of two new ultracool dwarf systems from WISE and 2MASS surveys, expanding the known sample of such systems and analyzing their properties and multiplicity.

Contribution

It introduces two new ultracool dwarf systems with main sequence stars, enhancing the catalog of known systems and providing insights into their multiplicity and unresolved binaries.

Findings

Discovered two new ultracool dwarf systems with main sequence stars.

Estimated physical properties of the new systems, including luminosity and temperature.

Discussed the binary fraction and unresolved multiplicity among ultracool dwarfs.

Abstract

We have used the 2MASS all-sky survey and the WISE to look for ultracool dwarfs that are part of multiple systems containing main sequence stars. We cross-matched L dwarf candidates from the surveys with Hipparcos and Gliese stars, finding two new systems. The first system, G255-34AB is an L2 dwarf companion to a K8 star, at a distance of 36 pc. We estimate its bolometric luminosity as log (L/Lsolar) = -3.78 +/- 0.045 and Teff = 2080 +/- 260 K. The second system, GJ499ABC, is a triple, with an L5 dwarf as a companion to a binary with an M4 and K5 star. These two new systems bring the number of L dwarf plus main sequence star multiple systems to twenty four, which we discuss. We consider the binary fraction for L dwarfs and main sequence stars, and further assess possible unresolved multiplicity within the full companion sample. This analysis shows that some of the L dwarfs in this sample might actually be unresolved binaries themselves, since their MJ appears to be brighter than the expected for their spectral types.