Astrophysical Parameters and Habitable Zone of the Exoplanet Hosting   Star GJ 581
  GJ 581 is an M dwarf host of a multiplanet system. We use long-baseline interferometric measurements from the CHARA Array, coupled with trigonometric parallax information, to directly determine its physical radius to be $0.299 \pm 0.010 R_{\odot}$. Literature photometry data are used to perform spectral energy distribution fitting in order to determine GJ 581's effective surface temperature $T_{\rm EFF}=3498 \pm 56$ K and its luminosity $L=0.01205 \pm 0.00024 L_{\odot}$. From these measurements, we recompute the location and extent of the system's habitable zone and conclude that two of the planets orbiting GJ 581, planets d and g, spend all or part of their orbit within or just on the edge of the habitable zone. 
Kaspar von Braun (1), Tabetha S. Boyajian (2,3), Stephen R. Kane (1),   Gerard T. van Belle (4), David R. Ciardi (1), Merced...
astro-ph.EP astro-ph.SR