Evolution of the Symbiotic Nova PU Vul -- Outbursting White Dwarf, Nebulae, and Pulsating Red Giant Companion

摘要

We present a composite light-curve model of the symbiotic nova PU Vul (NovaVulpeculae 1979) that shows a long-lasted flat optical peak followed by a slowdecline. Our model light-curve consists of three components of emission, i.e.,an outbursting white dwarf (WD), its M-giant companion, and nebulae. The WDcomponent dominates in the flat peak while the nebulae dominate after thephotospheric temperature of the WD rises to log T (K) >~ 4.5, suggesting its WDorigin. We analyze the 1980 and 1994 eclipses to be total eclipses of the WDocculted by the pulsating M-giant companion with two sources of the nebularemission; one is an unocculted nebula of the M-giant's cool-wind origin and theother is a partially occulted nebula associated to the WD. We confirmed ourtheoretical outburst model of PU Vul by new observational estimates, thatspanned 32 yr, of the temperature and radius. Also our eclipse analysisconfirmed that the WD photosphere decreased by two orders of magnitude betweenthe 1980 and 1994 eclipses. We obtain the reddening E(B-V) ~ 0.3 and distanceto PU Vul d ~ 4.7 kpc. We interpret the recent recovery of brightness in termsof eclipse of the hot nebula surrounding the WD, suggesting that hydrogenburning is still going on. To detect supersoft X-rays, we recommend X-rayobservations around June 2014 when absorption by neutral hydrogen is minimum.