2007ApJS..171..249H

The first observations of the ultraviolet spectrum of the binary system VV Cep (M2 Iab+B?) during total eclipse have been made with the HST. A rich emission-line spectrum is seen, with over two thousand emission features present. Shortward of 1600 Å, a weak continuum presumably due to Rayleigh scattering of the hot component is present, strengthening markedly shortward of 1500 Å. The continuum of the M supergiant becomes apparent longward of 2650 Å. Numerous circumstellar and interstellar absorption features are also seen. We present an atlas of the spectrum from 1300-3160 Å as observed near midtotality and at two epochs closer to egress, when gas surrounding the hot component has begun to emerge from eclipse and the flux on the short-wavelength edges of many emission lines has increased. This atlas has been annotated with line identifications. The majority of the emission lines arise from singly ionized elements in the iron group with upper levels up to 14 eV, and generally correspond to absorption features seen out of eclipse. Circumstellar and interstellar absorption features seen out of eclipse remain in absorption during totality and are also annotated on the atlas. Well over 90% of the emission features have plausible identifications, but there are many blends. Only a few hundred features appear to be free enough from blending for useful measurement of the peak flux in the line. We present a list of these unblended features.