Three active M dwarfs within 8 pc: L 449-1, L 43-72, and LP 949-15

Abstract

Three nearby star candidates were selected as bright 2MASS point sources without associated optical sources, i.e. with potentially large proper motions, subsequently confirmed by multi-epoch optical data from the SuperCOSMOS Sky Surveys. All three objects are listed in the NLTT catalogue of high proper motion stars. Follow-up spectroscopic observations allowed us to classify L 449-1 as M 4.0e dwarf at 5.7 pc, L 43-72 as M 4.5e dwarf at 7.2 pc, and LP 949-15 as M 5.0e dwarf at 6.1 pc, using known absolute JHKs magnitudes of dwarfs with corresponding spectral types, respectively. All three stars exhibit Hα emission lines, and all three can be identified with bright X-ray sources. The available ROSAT light curves of two of the objects show typical flare-like variability. Thus, all three stars are active, very close potential neighbours of the Sun, previously not mentioned as such, certainly deserving further attention. In particular, these are very promising candidates for trigonometric parallax programs.