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X-ray and UV observations of nova V598 Puppis between 147 and 255 days after outburst
journal contributionposted on 2012-10-24, 09:06 authored by K. L. Page, J. P. Osborne, A. M. Read, P. A. Evans, A. P. Beardmore, J-U. Ness, M. Bode, G. J. Schwarz, S. Starrfield
Aims. The launch of Swift has allowed many more novae to be observed regularly over the X-ray band. Such X-ray observations of novae can reveal ejecta shocks and the nuclear burning white dwarf, allowing estimates to be made of the ejecta velocity. Methods. We analyse XMM-Newton and Swift X-ray and UV observations of the nova V598 Pup, which was initially discovered in the XMM-Newton slew survey. These data were obtained between 147 and 255 days after the nova outburst, and are compared with the earlier, brighter slew detection. Results. The X-ray spectrum consists of a super-soft source, with the soft emission becoming hotter and much fainter between days ~147 and ~172 after the outburst, and a more slowly declining optically thin component, formed by shocks with kT ~ 200–800 eV (corresponding to velocities of 400–800 km s[superscript: -1]). The main super-soft phase had a duration of less than 130 days. The Reflection Grating Spectrometer data show evidence of emission lines consistent with optically thin emission of kT ~ 100 eV and place a limit on the density of the surrounding medium of log (n[subscript: e]/cm[superscript: -3]) < 10.4 at the 90% level. The UV emission is variable over short timescales and fades by at least one magnitude (at λ ~ 2246–2600 $\AA$) between days 169 and 255.