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ATEL # 1202; Thomas Nelson and Marina Orio (INAF-Padova and U Wisconsin), and see below full list
on 1 Sep 2007; 23:00 UT
Password Certification: Marina Orio (email@example.com)
Subjects: X-ray, Nova
AUTHORS, FULL LIST: Thomas Nelson and Marina Orio (INAF-Padova and U Wisconsin), Howard Bond (HST), Jeremy Drake (CfA), Neal Gehrels and Koji Mukai (GSFC), Robert Gehrz, C. Woodward and M. Wagner (U. Minnesota), Margarida Hernanz Carbo (IEEC-CSIC), Peter Hauschild (U Hamburg), Ian-Uwe Ness and Sumner Starfield (ASU), Emre Tepedelenlioglu (Penn State). Nova V5116 Sgr (Nova Sgr 2005b, see Ness et al. 2007, CBET #1030) was observed in X-rays with the Chandra LETG grating and the HRC-S camera on 2007 August 28 for about 35000 seconds. The nova was detected as a bright supersoft source, with a net 1st order count rate of 0.32 cts/s. The spectrum shows a soft continuum with several bright emission lines superimposed. The X-ray spectrum can be fitted with a white dwarf atmospheric model developed by Hartmann for Nova LMC 1995 (Orio, Hartmann, Still et al. 2003, ApJ594, 435). The best fit to the continuum indicates an intervening hydrogen column density N(H)=4.3x10(21) cm(2), a temperature of 465,000 K, and a luminosity in the 0.2-1 keV range 1.1 x 10(37) x d(kpc)(2). The system of superimposed emission lines includes the He-like triplet of N VI and the Ly alpha and betalines of C VI, although no identification of the remaining lines can be made assuming that they originate in a plasma with a common velocity. The count rate rate increased twice by a factor of ~5 for periods of about 1000 seconds, then it decreased abruptly to the pre-flare level. A similar time variability was observed with XMM-Newton on March 5 2007 (Sala, Hernanz & Ferri, ATel #1184).