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Durham University

Department of Physics

Staff profile

Publication details for Dr Nigel Metcalfe

Deacon, N. R., Magnier, E. A., Liu, M. C., Schlieder, J. E., Aller, K. M., Best, W. M. J., Bowler, B. P., Burgett, W. S., Chambers, K. C., Draper, P. W., Flewelling, H., Hodapp, K. W., Kaiser, N., Metcalfe, N., Sweeney, W. E., Wainscoat, R. J. & Waters, C. (2017). 2MASS 0213+3648 C: A wide T3 benchmark companion to an an active, old M dwarf binary. Monthly Notices of the Royal Astronomical Society 467(1): 1126-1139.

Author(s) from Durham


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-STARRS 1 data and despite its relative proximity to the Sun (22.2

pc; Pan-STARRS 1 parallax) and brightness (J = 15.3), it 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 Hα emission and shows evidence for UV flares. The binary's weak GALEX UV emission and strong Na i 8200 Å Na absorption lead us to an age range of ∼1–10 Gyr. Applying this age range to evolutionary models implies that the wide companion has a mass of 0.063 ± 0.009 M⊙. 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.