Central Bureau for Astronomical Telegrams
IAUC 5065: 1990S; NOTICE TO SUBSCRIBERS
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Circular No. 5065
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 or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
SUPERNOVA 1990S IN MCG -05-29-006
M. Phillips, Cerro Tololo Interamerican Observatory; and
C. Gouiffes, European Southern Observatory, report: "Further
low-dispersion spectra (range 340-950 nm) were obtained on July
26 UT with the CTIO 4-m and ESO 3.6-m telescopes. These show narrow
(<= 500 km/s FWHM) emission lines of H I and He I at a redshift
of 0.0256 superposed on a strong, featureless continuum. A weak
emission line at an observed wavelength of 514.1 nm may be due to
[O III] 500.7-nm but is perhaps more consistent with He I 501.5-nm.
A weak feature in the red wing of H-alpha was thought to be
[N II] 658.4-nm emission (cf. IAUC 5058) but could also be
interpreted as structure in the H-alpha profile. The weakness of
the forbidden transitions and the unusual strengths of the He I
lines are reminiscent of the early emission-line spectra of certain
galactic novae and probably indicate a condition of high electron
density. We suggest that the emission lines arise in a
circumstellar shell that has been ionized by the ultraviolet
radiation of the supernova. Similar narrow emission lines were
observed in the type IIl supernovae 1979C and 1984E (Branch et al.
1981, Ap.J. 244, 780; Dopita et al. 1984, Ap.J. 287, L69; Henry
and Branch 1987, P.A.S.P. 99, 112) but disappeared within a few
weeks after outburst."
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1990 July 28 (5065) Brian G. Marsden
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