| Abstract: | We present the results of our analysis of the spectrophotometric and photometric data for the symbiotic nova PU Vul acquired
in 2001–2008. The continuum in the optical observed in 2006–2008 cannot be reconciled with a standard model including light
from the cool component, hot component, and nebula. The hot component’s temperature increased to 194 000 K by 2008, while
its luminosity decreased by a factor of ten compared to the plateau of 1979–1991. The evolution of the hot component as reflected
by the Hertzsprung-Russell diagram does not agree with a theoretical model describing the evolution of a thermonuclear outburst
in a white-dwarf envelope. We estimate the mass of the hot component to be 0.5M
⊙ based on the luminosity of the hot component during the plateau stage. Our spectroscopy reveals periodic continuum-flux variations
due to brightness variability of the cool component, with an amplitude of at least 2
m
at 7000 ?. The spectral type of the cool component in 2008 was M6.3. |
