V605 Aquilae — The Most Extreme Hydrogen-Poor Object
V605 Aquilae, whose novalike outburst was observed in 1919, is the central object of the old planetary nebula A58. It is the only ‘nova’ known with a hydrogen-deficient carbon-rich outburst spectrum and a remnant consisting of a WC-type star and a nebula which appears to be totally void of hydrogen. The star shows a red continuum of magnitude 22.3 and a prominent line of CIV 580.8 nm with a total width of 4400 km/sec. Other lines are extremely weak. The remnant nebula shows only forbidden lines of heavy elements. The strongest ones are due to the nebular transitions of [0 III], [NII], [0I]. IR [0II] is present, other ions are suspected. The nebula is an IRAS point source of temperature 170 K.