SIMBAD references

J.-U. Ness and S. Starrfield, Arizona State University; J. J. Drake, Smithsonian Astrophysical Observatory; M. Orio, Istituto Nazionale di Astrofisica and University of Wisconsin; R. Gonzalez-Riestra, XMM-Newton Science Operations Center, European Space Agency; M. F. Bode, Liverpool John Moores University; T. J. O'Brien and R. J. Davis, University of Manchester; J. P. Osborne, K. L. Page, A. Beardmore, and M. Goad, University of Leicester; G. Schwarz, West Chester University; J. Krautter, University of Heidelberg; A. Evans, Keele University; S. P. S. Eyres, University of Central Lancashire; R. Gehrz and C. Woodward, University of Minnesota; and N. A. Gehrels, NASA Goddard Space Flight Center, report on initial high-resolution x-ray spectra of the outburst of RS Oph (cf. IAUC 8671) obtained during the Super-Soft-Source (SSS) phase. RS Oph was observed with the Chandra X-ray Observatory Low Energy Transmission Grating and HRC-S detector (LETGS) in the wavelength range 0.3-17.0 nm (0.07-4 keV) on Mar. 24 for 10000 s and on Apr. 20 for 6500 s, as well as on Apr. 7 for 18000 s with all XMM-Newton instruments, including the Reflection Grating Spectrometer (RGS) in the wavelength range 0.5-3.8 nm (0.3-2 keV). All three observations show a strong, soft continuum between 1.5 nm (0.8 keV) and 4 nm (0.3 keV) with line absorption and emission. The spectra resemble, but peak at a higher energy than, the LETGS spectrum of V4743 Sgr obtained during the SSS phase (Ness et al. 2003, Ap.J. 594, L127). In the Mar. 24 spectrum, the continuum can be roughly fitted with an absorbed Planck function of temperature 750000 K and NH = 3.7 x 10**(21) cm**(-2). In contrast, neither the RGS spectrum of Apr. 7 nor the LETGS spectrum of Apr. 20 can be fitted with a simple absorbed Planck function. The Mar. 24 spectrum shows P-Cyg-type line profiles of resonance lines including O VIII, N VII, and Fe XVII, in which the blue-shifted component extends to 1300-1800 km/s and the red-shifted one peaks at velocities from 100 to 500 km/s. Shortward of 1.5 nm, emission lines are identified from H-like and He-like ions of Si, Mg, and Ne that are blue-shifted by less than 1000 km/s. These lines are weaker in the two later grating (RGS and LETGS) observations, in the sense that the P-Cyg profiles are less pronounced and most red-shifted emission lines have disappeared. The first light curve obtained on Mar. 24 corresponds to an extremely unstable phase in the evolution of the SSS (http://www.astronomerstelegram.org/?read=801) and is highly variable with an average flux level of 1.3 x 10**(-9) erg/cm**2/s. The other two grating observations from Apr. 7 [3.0 x 10**(-9) erg/cm**2/s] and Apr. 20 [3.2 x 10**(-9) erg/cm2/s] revealed a brighter source. This last Apr. 20 observation was taken during the slow and stable decay now exhibited by RS Oph (http://www.astronomerstelegram.org/?read=801), and the lightcurve is constant. The 35-s period found in some Swift observations (http://www.astronomerstelegram.org/?read=770) is not found in any of the grating observations, which is consistent with the times at which this behavior was observed, as reported at http://www.astronomerstelegram.org/?read=801. Continued monitoring of the source at all wavelengths is encouraged.