We report on the discovery of a very low mass ( VLM ) star in the solar neighborhood , originally identified as an optical counterpart of a flaring X - ray source detected in the ROSAT All-Sky survey .
Optical spectroscopy and infrared photometry consistently reveal a spectral type of M 9 \pm 0.5 and a distance of \approx 11 \pm 2 pc .
The optical counterpart of 1RXS~J115928.5 $ - $ 524717 shows a large proper motion of 1.08 \pm 0.06 \arcsec /year . 1RXS~J115928.5 $ - $ 524717 is the fourth object among the VLM stars displaying a huge X - ray flare , reaching the unprecedent value of L _ { X } / L _ { bol } ~ { } \simeq 0.1 .