The nearby M-dwarf system Gliese 866 revisited

We present an improved orbit determination for the visual pair in the M-dwarf triple system Gliese 866 that is based on new speckle-interferometric and HST observations. The system mass is M = 0.34+/- 0.03 M_sun. The masses of the components derived using the mass-luminosity relation are consistent with this mass sum. All three components of Gliese 866 seem to have masses not far from the hydrogen burning mass limit. Based on observations collected at the German-Spanish Astronomical Center on Calar Alto, Spain, and at the European Southern Observatory, La Silla, Chile