Classical novae in outburst: evolution of the ultraviolet emission lines in CO novae
INAF, Istituto di Fisica dello Spazio Interplanetario, Via del Fosso del Cavaliere 100, 00133 Rome, Italy e-mail: email@example.com
2 Dipartimento di Fisica E. Amaldi, Università Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy
3 XMM Science Operation Centre, ESAC, Villafranca Satellite Tracking Station, PO Box 50727, 28080 Madrid, Spain
Accepted: 11 March 2005
A comparative study is made of the temporal changes of the ionization level in seven CO novae well monitored with the IUE satellite at low resolution. The investigation is based on the evolution of the fluxes in eight strong ultraviolet emission lines covering a wide range of ionization potentials, from (7.6 eV) to (77.5 eV). We find that the rate of increase of the ionization conditions in the emitting regions is uniform in the sample of novae considered, provided the time scale is normalized to the optical decay time t3. The implications of this result for the nova ejected masses and for the nuclear turnoff time are discussed.
Key words: stars: novae, cataclysmic variables / techniques: image processing / ultraviolet: stars / methods: data analysis
© ESO, 2005