* Astronomy

Title: 2MASS J01542930+0053266 : A New Eclipsing M-dwarf Binary System
Authors: A.C.Becker, E.Agol, N.M.Silvestri, J.J.Bochanski, C.Laws, A.A.West, G.Basri, V.Belokurov, D.M.Bramich, J.M.Carpenter, P.Challis, K.R.Covey, R.M.Cutri, N.W.Evans, M.Fellhauer, A.Garg, G.Gilmore, P.Hewett, P.Plavchan, D.P.Schneider, C.L.Slesnick, S.Vidrih, L.M.Walkowicz, D.B.Zucker

We report on 2MASS J01542930+0053266, a faint eclipsing system composed of two M dwarfs. The variability of this system was originally discovered during a pilot study of the 2MASS Calibration Point Source Working Database. Additional photometry from the Sloan Digital Sky Survey yields an assband lightcurve, from which we derive an orbital period of 2.6390157 ±0.0000016 days. Spectroscopic followup confirms our photometric classification of the system, which is likely composed of M0 and M1 dwarfs. Radial velocity measurements allow us to derive the masses (M_1 = 0.66 ±0.03 M_sun; M_2 = 0.62 ±0.03 M_sun) and radii (R_1 = 0.64 ± 0.08 R_sun; R_2 = 0.61 ±0.09 R_sun) of the components, which are consistent with empirical mass-radius relationships for low-mass stars in binary systems. We perform Monte Carlo simulations of the lightcurves which allow us to uncover complicated degeneracies between the system parameters. Both stars show evidence of H-alpha emission, something not common in early-type M dwarfs. This suggests that binarity may influence the magnetic activity properties of low-mass stars; activity in the binary may persist long after the dynamos in their isolated counterparts have decayed, yielding a new potential foreground of flaring activity for next generation variability surveys.

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