Swift X-Ray and Ultraviolet Monitoring of the Classical Nova V458 Vul (Nova Vul 2007)

Ness, J.-U.; Drake, J. J.; Beardmore, A. P.; Boyd, D.; Bode, M. F.; Brady, S.; Evans, P. A.; Gaensicke, B. T.; Kitamoto, S.; Knigge, C.; Miller, I.; Osborne, J. P.; Page, K. L.; Rodriguez-Gil, P.; Schwarz, G.; Staels, B.; Steeghs, D.; Takei, D.; Tsujimoto, M.; Wesson, R.; Zijlstra, A.
Referencia bibliográfica

The Astronomical Journal, Volume 137, Issue 5, pp. 4160-4168 (2009).

Fecha de publicación:
5
2009
Número de autores
21
Número de autores del IAC
1
Número de citas
32
Número de citas referidas
28
Descripción
We describe the highly variable X-ray and UV emission of V458 Vul (Nova Vul 2007), observed by Swift between 1 and 422 days after outburst. Initially bright only in the UV, V458 Vul became a variable hard X-ray source due to optically thin thermal emission at kT = 0.64 keV with an X-ray band unabsorbed luminosity of 2.3 × 1034 erg s-1 during days 71-140. The X-ray spectrum at this time requires a low Fe abundance (0.2+0.3 -0.1 solar), consistent with a Suzaku measurement around the same time. On day 315 we find a new X-ray spectral component which can be described by a blackbody with temperature of kT = 23+9 -5 eV, while the previous hard X-ray component has declined by a factor of 3.8. The spectrum of this soft X-ray component resembles those typically seen in the class of supersoft sources (SSS) which suggests that the nova ejecta were starting to clear and/or that the white dwarf photosphere is shrinking to the point at which its thermal emission reaches into the X-ray band. We find a high degree of variability in the soft component with a flare rising by an order of magnitude in count rate in 0.2 days. In the following observations on days 342.4-383.6, the soft component was not seen, only to emerge again on day 397. The hard component continued to evolve, and we found an anticorrelation between the hard X-ray emission and the UV emission, yielding a Spearman rank probability of 97%. After day 397, the hard component was still present, was variable, and continued to fade at an extremely slow rate but could not be analyzed owing to pile-up contamination from the bright SSS component.
Proyectos relacionados
Representación de la variable cataclísmica SS Cygni (Chris Moran)
Estrellas Binarias
El estudio de las estrellas binarias es una parte esencial de la astrofísica estelar. Una gran parte de las estrellas de nuestra Galaxia y de otras galaxias se ha formado en sistemas binarios o múltiples, por lo que entender la estructura y evolución de estos sistemas es importante desde el punto de vista estelar y galáctico. Un aspecto en el que
Pablo
Rodríguez Gil