Spectroscopy and photometry of the symbiotic nova PU Vul during its nebular phase and minimum of 2007

• Published in: Astronomy reports Vol. 55; no. 10; pp. 896 - 910
• Main Authors: Tatarnikova, A. A., Tatarnikov, A. M., Esipov, V. F., Tarasova, T. N., Shenavrin, V. I., Kolotilov, E. A., Nadzhip, A. E.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01.10.2011; Springer Nature B.V
• Subjects: Astronomy; Astrophysics; Nebulae; Observations and Techniques; Physics; Physics and Astronomy; Spectroscopy; Astronomy Report; Spectral Type; Accretion Disk; White Dwarf; Spectral Energy Distribution
• ISSN: 1063-7729; 1562-6881
• DOI: 10.1134/S106377291110009X

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 0.5 M ⊙ 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 Å. The spectral type of the cool component in 2008 was M6.3.