Near-Infrared Spectroscopy of V1974 Cygni 1992: New Coronal Emission Lines in Classical Novae
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The near-infrared (1.2-2.4 m) spectrum of V1974 Cygni (Nova Cygni 1992) was observed on 1993 May 2 at a spectral resolution of 570 using the Ohio State University Infrared Imager/Spectrometer on the Perkins 1.8 m telescope. In agreement with previous infrared spectra of novae and V1974 Cyg in particular, we find emission lines of [Al IX], [Ca VIII], [Si VI], and [S IX] present in our spectra. However, contemporaneously with the appearance of enhanced soft X-ray emission observed by ROSAT in early 1993, we report the discovery of infrared coronal lines arising from ions not previously observed in classical novae. These include [P VIII] 1.737 m, [P VIII] 1.377 m, [Si X] 1.430 m, [S XI] 1.395 m, [Ti VI] 1.715 m, and possibly [Cr XI] 1.550 m and [Ti X] 1.332 m. Optical spectroscopy confirms the high degree of ionization and gives Te 20,000 K in the [Fe VIII] region. Photoionization from the hot white dwarf remnant can account for the high degree of ionization and relatively low excitation temperature of the ejecta. Our discovery of phosphorus in the ejecta when combined with the results of recent hydrodynamic studies of accretion onto white dwarfs suggests that the white dwarf in V1974 Cyg 1992 must be extremely massive. 1996. The American Astronomical Society. All rights reserved.
