Electronic Telegram No. 415
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
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RS OPHIUCHI
     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; M. F. Bode,
Liverpool John Moores University; T. J. O'Brien and R. J. Davis,
University of Manchester; J. Osborne and K. L. Page, 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; and R. Gehrz and C. Woodward,
University of Minnesota, report on the first high-resolution x-ray
spectra of the outburst of the recurrent nova RS Oph (cf. IAUC 8671),
obtained on Feb. 26 (two weeks after the beginning of the outburst).
The Chandra X-ray Observatory High Energy Transmission Grating and
ACIS-S detector observed RS Oph for 10000 s in the wavelength range
0.15-2.5 nm, revealing a rich emission-line spectrum dominated by
resonance lines of He-like and H-like ions of Fe, S, Si, Mg, and Ne
superimposed on a strong continuum.  The lines seen indicate that a
wide range of plasma temperatures have been observed:  the coolest
transition detected is the O VIII Lyman_alpha doublet at 1.897 nm
(emissivity peak at T = 3 MK), while the hottest is the Fe XXV 1s2p-1s2
resonance line (emissivity peak at T = 60 MK).  Lines show broadening
corresponding to approximately 2000 km/s at half maximum, with
systematic blueshifts amounting to approximately 500 km/s (Si XIV, Mg
XII, and Ne X) and 1000 km/s (O VIII).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2006 CBAT
2006 March 2                     (CBET 415)               Daniel W. E. Green