2MASS 0213+3648 C: A wide T3 benchmark companion to an an active, old M dwarf binary

N. R. Deacon, E. A. Magnier, Michael C. Liu, Joshua E. Schlieder, Kimberly M. Aller, William M. J. Best, Brendan P. Bowler, W. S. Burgett, K. C. Chambers, P. W. Draper, H. Flewelling, K. W. Hodapp, N. Kaiser, N. Metcalfe, W. E. Sweeney, R. J. Wainscoat, C. Waters

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
54 Downloads (Pure)


We present the discovery of a 360 AU separation T3 companion to the tight (3.1 AU) M4.5+M6.5 binary 2MASS J02132062+3648506. This companion was identified using Pan-STARRS1 data and, despite its relative proximity to the Sun (22.2$_{-4.0}^{+6.4}$ pc; Pan-STARRS1 parallax) and brightness ($J$=15.3), appears to have been missed by previous studies due to its position near a diffraction spike in 2MASS. The close M~dwarf binary has active X-ray and H$\alpha$ emission and shows evidence for UV flares. The binary's weak {\it GALEX} UV emission and strong Na I 8200\AA Na absorption leads us to an age range of $\sim$1-10Gyr. Applying this age range to evolutionary models implies the wide companion has a mass of 0.063$\pm$0.009\,$M_{\odot}$. 2MASS J0213+3648 C provides a relatively old benchmark close to the L/T transition and acts as a key, older comparison to the much younger early-T companions HN~Peg~B and GU~Psc~b.
Original languageEnglish
Pages (from-to)1126-1139
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Early online date24 Jan 2017
Publication statusPublished - 1 May 2017


  • astro-ph.SR


Dive into the research topics of '2MASS 0213+3648 C: A wide T3 benchmark companion to an an active, old M dwarf binary'. Together they form a unique fingerprint.

Cite this