Central Bureau for Astronomical Telegrams
IAUC 5748: 1993J
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Circular No. 5748
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
SUPERNOVA 1993J IN NGC 3031
H. U. Zimmermann, Max-Planck-Institut fur Extraterrestrische
Physik (MPE); W. Lewin and E. Magnier, Massachusetts Institute of
Technology; P. Predehl, G. Hasinger, W. Pietsch, B. Aschenbach and
J. Trumper, MPE; G. Fabbiano, Center for Astrophysics; J. van Paradijs,
University of Amsterdam; L. Lubin, Princeton University; and R. Petre,
Goddard Space Flight Center, communicate: "We observed SN 1993J with
ROSAT on Apr. 3.4 UT. In a 2826-s exposure using the PSPC detector
the supernova shows up as a bright new source within 10" of the
optical position as given on IAUC 5731. At this time only raw
telemetry data are available, so a calibrated x-ray position has to
await the final attitude solution. The x-ray supernova is located
about 1' northwest of a bright x-ray source that was already detected
by Einstein and ROSAT (source X-6 in the paper by Fabbiano 1988,
Ap.J. 325, 544). A first estimate of the intensity shows that the
supernova is about 1.7 times stronger than X-6 in soft x-rays."
A. C. Porter and L. A. Wells, Kitt Peak National Observatory,
report: "A high-resolution (0.08 nm) spectrum taken by V. C. Rubin at
the KPNO 4-m telescope on Mar. 31.19 UT shows a low-contrast (EW
= 0.014 nm) feature centered at 656.5 nm. Interpreted as H alpha,
this corresponds to a radial velocity of about 150 km/s relative to the
systemic value for M81. Several weak (EW = 0.003 nm) absorption features
are visible in the region from 645 to 670 nm. The 656.5-nm line is
almost certainly the same one reported by Filippenko and Matheson on
IAUC 5740. At high resolution, it shows a sharp blue edge, a sloping
red side and a probable weak absorption feature at its center. Such a
line profile is consistent with emission from a dusty or thick shell or
sphere, perhaps from a wind phase late in the progenitor's lifetime.
The line's FWHM is 1.2 nm, corresponding to a shell velocity of 300 km/s.
Such a shell should be consumed by the supernova shock within a few
weeks or months, causing the disappearance of this line over the same
timescale, as in the more dramatic example of SN 1984E (cf. IAUC 5742).
High-resolution observations of this and the other faint lines reported
on IAUC 5740 are strongly urged to follow the evolution of this feature."
A. V. Filippenko, University of California at Berkeley, reports that
M. Lehnert (Lawrence Livermore National Laboratory) and P. Butler (also of
Berkeley) obtained a high-dispersion spectrum of SN 1993J on Mar. 31 UT
with the Shane 3-m reflector at the Lick Observatory. The resolution
of approximately 0.015 nm reveals four strong components and several
weak ones in the Na I D interstellar absorption lines.
1993 April 5 (5748) Brian G. Marsden
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