X-RAY GRATING OBSERVATIONS OF RECURRENT NOVA T PYXIDIS DURING THE 2011 OUTBURST

Abstract

The recurrent nova T Pyx was observed with the X-ray gratings of Chandra and\nXMM-Newton, 210 and 235 days, respectively, after the discovery of the 2011\nApril 14 outburst. The X-ray spectra show prominent emission lines of C, N, and\nO, with broadening corresponding to a full width at half maximum of ~2000-3000\nkm/s, and line ratios consistent with high-density plasma in collisional\nionization equilibrium. On day 210 we also measured soft X-ray continuum\nemission that appears to be consistent with a white dwarf (WD) atmosphere at a\ntemperature ~420,000 K, partially obscured by anisotropic, optically thick\nejecta. The X-ray continuum emission is modulated with the photometric and\nspectroscopic period observed in quiescence. The continuum at day 235 indicated\na WD atmosphere at a consistent effective temperature of 25 days earlier, but\nwith a lower flux. The effective temperature indicates a mass of ~1 solar mass.\nThe conclusion of partial WD obscuration is supported by the complex geometry\nof non-spherically-symmetric ejecta confirmed in recent optical spectra\nobtained with the Southern African Large Telescope (SALT) in November and\nDecember of 2012. These spectra exhibited prominent [O III] nebular lines with\nvelocity structures typical of bipolar ejecta.\n