An illumination effect and an eccentric orbit for the symbiotic binary PU Vul revealed by 32 years of optical spectroscpy

CÚNEO, V. A., KENYON, S. J., GOMEZ, M., CHOCHOL, D., SHUGAROV, S. Y., KOLOTILOV, A. E.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018 vol. 479 p. 2728 - 2742

0035-8711

We analyse ∼ 32 yr of optical spectra and photometry for the symbiotic binary PU Vul. Light curves for the He I lambda 4471, He II lambda 4686, and Hbeta lambda 4861 emission lines reveal an illumination effect, where the hot white dwarf ionizes the outflowing wind of the red giant, and evidence for an eccentric orbit with e > 0.16. Along with the gradual appearance of high ionization emission from [Fe VII] and OVI, the relative fluxes of these lines suggest an increase in the effective temperature of the hot component, from roughly 10^5 K on JD 244 8000 (1990) to roughly 2 times 10^5 K on JD 245 5000 (2009). During this period, the luminosity of the hot component dropped by a factor of 4?6 to a current value of roughly 1000 L_Sun.