Two new ultracool benchmark systems from WISE+2MASS

Gomes, J. I.; Pinfield, D. J.; Marocco, F.; Day-Jones, A. C.; Burningham, B.; Zhang, Z. H.; Jones, H. R. A.; Spaandonk, L. van; Weights, D.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 431, Issue 3, p.2745-2755

Advertised on:
5
2013
Number of authors
9
IAC number of authors
0
Citations
33
Refereed citations
28
Description
We have used the Two-Micron All-Sky Survey and the Wide-field Infrared Survey Explorer 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/L⊙ = -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 24, 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.