A NEW LOOK AT HW VIRGINIS

New BVR photometry of the ultra-short period eclipsing binary HW Vir i s presented. The light curves were analyzed with the Wilson-Devinney s ynthesis method. The primary component is found to be a hot sdB subdwa rf with the mass M(1) = 0.5 M., radius R(1) = 0.18 R. and the effectiv e temperature T-1 = 26000 K. The secondary component with the temperat ure T-2 = 3250 K, mass M(2) = 0.15 M. and R(2) = 0.18 R. is placed on the H-R diagram close to the main sequence, but is somewhat hotter tha n typical dM star of the same mass. The illuminated hemisphere of the cool star is heated to the mean temperature of about 9000 K. The hot c omponent is a typical Extended Horizontal Branch star at the beginning of the core helium burning. Its evolutionary status appears to be pra ctically unaffected by close proximity of the cool low-mass companion. The binary HW Vir will most likely become a cataclysmic variable with the period 0.08 days on the time scale of 1.8 billion years.