Nova V1974 Cygni 1992 has been accepted as a prototype of classical nova owing to its unique data set in almost all wavelengths. We present a further analysis of the archival X-ray data obtained by ROSAT PSPC on several pointings from 1992 April 22 to 1993 December 3. The soft X-ray emission arising from the H-burning white dwarf envelope (between 0.1-0.7 keV energy range) is fit with a new nova blackbody emission model that accounts for the absorption of X-ray photons by enhanced abundances in the white dwarf atmosphere (MacDonald 1994, private communication). A complete evolution of the white dwarf on a Hertzsprung-Russell diagram is presented using two different atmosphere models of NeO and CO rich compositions. The soft X-ray flux derived using the new NeO blackbody model is in the range (1.7-2.3)x 10(-7) erg\ s(-1) \ cm(-2) during the constant bolometric luminosity phase. The peak photospheric temperature ~ 51 eV (5.9 x 10(5) K) is reached at about day 500 with a photospheric radius of (0.96-1.4)x 10(9) cm for a 2-3 kpc source distance. In addition, we present the spectral development of the hard X-ray emission above 0.7 keV thought to originate from shocks within the nova wind. The hard X-ray emission evolves independently from the soft component reaching a maximum ~ 150 days after the outburst with a peak unabsorbed flux ~ 1.8 x 10(-11) \ erg\ s(-1) \ cm(-2) . The total hard X-ray energy dissipated in the ejecta is about 0.01 % of the initial explosion energy.
American Astronomical Society Meeting Abstracts #188
- Pub Date:
- May 1996