V723 Cas: A Dying Nova or a New-born SSS?
Abstract
The old Classical Nova V723 Cas (1995) was detected in X-rays with the XRT aboard Swift. Recent observations of optical emission lines from highly ionized iron motivated the 7-ksec observation, and the nova was observed to still be active with an X-ray emission level of 7.8 x 10-13 erg/cm2/s. The spectrum is that of a Super-Soft-Source (SSS) and peaks at about 0.4 keV. An absorbed blackbody with T ~ 320,000 K (about 27 eV), NH = 1.7 x 1021 cm-2 and RWD ~ 6000 km (log LX=36.4) results in a remarkably good fit to the spectrum. The fact that V723 Cas was found with a SSS spectrum 11 years after the outburst makes this a candidate for a classical nova that has evolved into a permanent SSS according to theoretical calculations by our group. If further observations show that it is still on, we have likely witnessed the white dwarf in a Classical nova beginning its growth to the Chandrasekhar limit.
- Publication:
-
High Resolution X-ray Spectroscopy: towards XEUS and Con-X
- Pub Date:
- August 2006
- Bibcode:
- 2006hrxs.confE..25N