Central Bureau for Astronomical Telegrams
IAUC 4514: 1987N; 1987A
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Circular No. 4514
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-495-7244/7440/7444
SUPERNOVA 1987N IN NGC 7606
H. E. Schwarz, M. H. M. Heemskerk and L. Mantegazza, European
Southern Observatory, telex: "We have taken spectra of SN 1987N
(range 560-900 nm, dispersion 22.8 nm/mm). These show very strong
H alpha and strong Na D line absorption, indicating it to be of type
II. The H alpha heliocentric blueshifts are 11 300, 21 400 and 29 600
km/s for the red edge, absorption trough and blue edge, respectively.
For Na D the corresponding velocities are 1700, 8800 and
12 100 km/s. Johnson V magnitudes and Walraven colors: Dec. 15.04
UT, V = 13.9; Dec. 16.04, V = 13.7, V-B = +0.072, B-U = +0.204,
U-W = +0.053, B-L = +0.094. SN 1987N is still brightening and has
extreme velocities, especially for a type-II object."
SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
N. Panagia, Space Telescope Science Institute (for the European
Target-of-Opportunity Team); R. Gilmozzi, A. Cassatella and
W. Wamsteker, ESA IUE Observatory; R. P. Kirshner, Center for
Astrophysics; and G. Sonneborn, IUE Observatory, Goddard Space
Flight Center, report: "A high-dispersion spectrum taken with the
SWP camera of IUE on Nov. 25 reveals that the emission lines that
were unresolved in the low-dispersion spectra (IAUC 4410, 4435)
are still unresolved, implying intrinsic widths smaller than 30
km/s. The detection is highly significant for the [C III] 190.668
and 190.873 nm and [N III] 174.967, 175.216 and 175.398 nm lines,
whereas it is marginal for the He II 164.043 nm and [N IV] 148.332
and 148.650 nm lines. The average radial velocity is 284 +/- 6
km/s, which agrees very well with the highest velocity component
found in the ultraviolet interstellar absorption spectrum. The
line intensities coincide with those measured in low dispersion
spectra at recent epochs, indicating that the bulk of the emission
is contained in the very narrow components detected in this high-
dispersion spectrum. The relative intensities of the [C III]
doublet components imply electron densities of the order of 2 x
10**4 cm-3. The very small line widths, together with the strong
nitrogen overabundance and the relatively low electron density,
confirm our earlier suggestion that these lines originate from
circumstellar material that had been ejected by the supernova
progenitor when it was a red supergiant."
Visual magnitude estimates by A. C. Beresford, Adelaide, S.
Australia: Dec. 12.50 UT, 6.2; 13.48, 6.2; 15.57, 6.3; 16.46, 6.1.
1987 December 16 (4514) Brian G. Marsden
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