Central Bureau for Astronomical Telegrams
IAUC 6665: 1987A; 1997bq
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Circular No. 6665
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
C. S. J. Pun, G. Sonneborn, C. Bowers, T. Gull, S. Heap, R.
Kimble, S. Maran, and B. Woodgate, Goddard Space Flight Center,
NASA, report for the Space Telescope Imaging Spectrograph (STIS)
Instrument Definition Team: "Medium-resolution spectral images
(range 481.8-510.4 and 629.5-686.7 nm, resolution about 6000) of SN
1987A and its circumstellar ring system were obtained with the
Hubble Space Telescope (+ STIS) on Apr. 26. The spectra were taken
through a 52" x 2" slit aligned with the major axis of the inner
ring. Spectral images (spatial FWHM about 0".10) of the inner ring
were obtained in H-alpha, H-beta, [O III] at 495.9 and 500.7 nm, [O
I] at 630.0 and 636.4 nm, [N II] at 654.8 and 658.3 nm, and [S II]
at 671.6 and 673.1 nm. The narrow emission lines (FWHM about 10
km/s) from the ring are not resolved spectrally in our data.
Emission features from the supernova debris (FWHM about 3000 km/s)
are dispersed and weakly detected only in H-alpha and H-beta. A
blueshifted emission feature, prominent in H-alpha and less so in
H-beta and [O I] 630.0-nm, originates on the inner ring at p.a. 31
+/- 8 deg (i.e., in the ring's northeast quadrant), believed to be
part of the ring tilted toward the earth. The H-alpha emission
from this point has a blue emission wing extending to -250 km/s;
there is no redshifted emission. This suggests that the
blueshifted emission is excited by interaction between high-
velocity gas streaming toward us and material in or close to the
inner ring. However, the velocity width of this feature is an
order of magnitude narrower than that expected from circumstellar
interaction models (e.g., Borkowski et al. 1997, Ap.J. 476, L31).
Portions of the outer rings (Burrows et al. 1995, Ap.J. 452, 680)
are also detected in H-alpha and [N II] emission. In [N II] 658.3-
nm, the portion of the northern outer ring that crosses the
supernova debris disappears at the position of the debris in our
spectra, where there is a gap of about 0".3 in the outer ring,
indicating that this section is located behind the debris. The
STIS spectral images of SN 1987A in H-alpha, [N II], [S II], and [O
III] may be viewed at http://oposite.stsci.edu/pubinfo/PR/97/14.html."
SUPERNOVA 1997bq IN NGC 3147
Unfiltered CCD magnitudes from S. Moretti and S. Tomaselli,
Forli, Italy, obtained with a 0.35-m telescope: May 2.9 UT, 15.0;
14.93, 15.6 (GSC comparison stars).
(C) Copyright 1997 CBAT
1997 May 20 (6665) Daniel W. E. Green
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