A Far Ultraviolet Study of the Nova-Like V794 Aquilae.
V794 Aql was observed in a high state with the Hubble Space Telescope Space Telescope Imaging Spectrograph (HST STIS) on 2003 August 28, and with the Far Ultraviolet Spectroscopic Explorer (FUSE) on 2004May 13. We present here a spectral analysis of the FUSE and HST STIS spectra. For a 0.9M_, the best fit is an accretion disk with a mass accretion rate M 1/4 10_8:5 to 10 8.0M yr_1 with an inclination of 60_ when assuming E(B-V ) 1/4 0:2. The corresponding distance to the system is d 1/4 690 pc. A single white dwarf model leads to a rather hot temperature (between 30,000 and 55,000 K depending on the assumptions) but does not provide a fit as good as the accretion disk model. The same disk model is the best fit to the FUSE spectrum, the HST STIS spectrum, and the combined FUSE + HST STIS spectrum, implying therefore that the disk model is the best fit not only in the least _2 sense, but also as a consistent solution across a large-wavelength span of observation. We find that the model fits are in much better agreement with the dereddened spectra when E(B - V ) is large, as excess emission in the longer wavelengths renders the slope of the observed spectra almost impossible to fit, unless E(B -V ) 1/4 0:2 . A large reddening value is in agreement with the hydrogen column density we find, N(H i) 1/4 4:5 ; 1020 cm_2 and N(H2) 1/4 3 ; 1017 cm 2 and with the E(B- V ) value derived from the existing archival International Ultraviolet Explorer spectra.
|Main Author:||Godon, Patrick.|
|Other Authors:||Sion, Edward., Barrett, Paul., Szkody, Paula.|