Discovery of a Wide Low-mass Binary System in Upper Scorpius

Abstract

Using the near-infrared spectrometer SpeX and its slit-viewing camera at the IRTF, I have resolved a low-mass member of the Upper Scorpius OB association into a double star. From K-band images of the pair, DENIS-P J161833.2-251750.4 A and B, I measure a separation of 0.96" and a magnitude difference of dK=0.42 mag. I present resolved 0.8-2.5 micron spectroscopy of the two objects, both of which exhibit signatures of youth in the shape of their H- and K-band continua, demonstrating that both are members of Upper Scorpius rather than field stars. In addition, through a comparison to optically-classified pre-main-sequence objects, I derive a spectral type near M5 for each component, corresponding to a mass of ~0.15 Msun with the evolutionary models of Chabrier and Baraffe. The probability that this pair is composed of unrelated M-type members of Upper Scorpius is ~10^-5. When added to the recent discoveries of other wide, easily disrupted low-mass binaries, this new system further establishes that the formation of low-mass stars and brown dwarfs does not require ejection from multiple systems. These observations also indicate that wide low-mass binaries can form in OB associations as well as in smaller clusters where the previously known wide pairs have been found. Thus, the available data show no perceptible effect of star-forming environment on the prevalence of loosely bound low-mass systems.

5 pages

References in corpus (13)

• A Giant Planet Candidate near a Young Brown Dwarf
• Giant Planet Companion to 2MASSW J1207334-393254
• Evidence for a co-moving sub-stellar companion of GQ Lup
• The First Discovery of a Wide Binary Brown Dwarf
• Discovery of Two Very Low-Mass Binaries: Final Results of an Adaptive Optics Survey of Nearby M6.0-M7.5 Stars
• Kelu-1 is a Binary L Dwarf: First Brown Dwarf Science from Laser Guide Star Adaptive Optics
• On the frequency of close binary systems among very low-mass stars and brown dwarfs
• Multiplicity at the Stellar/Substellar Boundary in Upper Scorpius
• The first wide ultracool binary dwarf in the field: DENIS-J055146.0-443412.2 (M8.5 + L0)
• An HST Search for Substellar Companions in the Young Cluster IC 348
• LP 349-25: a new tight M8V binary
• A young binary Brown Dwarf in the R-CrA star formation region
• Discovery of a widely separated binary system of very low mass stars

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