THE SUPERSOFT X-RAY PHASE OF NOVA RS OPHIUCHI 2006

摘要: Swift X-ray observations of the ~60 day supersoft phase recurrent nova RS Ophiuchi (RS Oph) 2006 show progress nuclear burning on white dwarf (WD) in exquisite detail. First seen 26 days after optical outburst, this started with extreme variability likely due to variable absorption, although intrinsic WD variations are not excluded. About 32 later, a steady decline count rate set in. NLTE model atmosphere spectral fits during that effective temperature increases from ~65 eV ~90 phase, falling slowly about 60 and more rapidly 80. The bolometric luminosity is be approximately constant close Eddington 45 up 60, subsequent possibly signaling end extensive burning. Before decline, multiply-periodic ~35 s modulation soft X-rays was present may signature fusion driven instability. Our measurements consistent mass near Chandrasekhar limit; combined deduced accumulation transferred its binary companion, leads us suggest Oph strong candidate for future supernova explosion. main uncertainty now whether CO type necessary Type Ia supernova. This confirmed by detailed abundance analyses spectroscopic data outbursts.