Central Bureau for Astronomical Telegrams
IAUC 4351: 1987A
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Circular No. 4351
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 1987A IN THE LARGE MAGELLANIC CLOUD
D. A. Allen and J. A. Bailey, Anglo-Australian Observatory; B. R.
Espey, Institute of Astronomy, University of Cambridge; R. D. Joseph
and A. Prestwich, Imperial College, London; and M. G. Smith and G. S.
Wright, U.K. Infrared Telescope, telex: "Optical and infrared
spectrometers on the AAT were used to observe SN 1987A during Mar. 13-19,
during which we found broad P-Cyg profiles in H-alpha and H-gamma
(Brackett), H-gamma and H-delta (Pfund), higher Brackett-series lines,
H-beta and H-gamma (Paschen), H-alpha (Balmer), and the Ca II 860-nm
group. The resolution through the infrared J, H, and K windows was about
1800. On Mar. 17, the P-Cyg profiles of most infrared lines covered a
characteristic range of radial velocity from about +3000 km/s (the reddest
extent of typical emission lines) to -4000 km/s. More extended
absorption was seen in the Paschen H-gamma profile, with absorption
extending to characteristic values near -6000 km/s and in H-alpha with
absorption extending to -13000 km/s and emission to +14000 km/s.
The minima in the absorption were observed at about -2000 km/s in the
Brackett series, about -3500 km/s in the Paschen series, and at -8500
km/s in H-alpha. Simple outflow models for the infrared lines suggest
that the radius of the ejected envelope is now about 2.5 times the
radius of the photosphere. Over the period Mar. 13-19, the continuum
flux increased from about 75 Jy to 130 Jy at 2.2 microns, and by a similar
factor at 4 microns. Over the same period, the velocity range of the
line profiles decreased by about 20 percent."
J. A. Bailey, Anglo-Australian Observatory; K. Ogura, Kogukakuin
University, Tokyo; and S. Sato, Kyoto University, report: "We
obtained infrared photometry and polarimetry of SN 1987A with the
Hatfield polarimeter on the Anglo-Australian Telescope. On Mar. 21
the infrared magnitudes were J = 2.57, H = 2.20, K = 1.98, L' =
1.66, and the following polarizations were measured (given by band,
percentage, and position-angle in degrees; estimated uncertainty is
given parenthetically in units of the last digit quoted): U, 0.51
(10), 58 (5); B, 0.61 (7), 37 (4); V, 0.49 (7), 47 (5); R, 0.53
(5), 40 (3); I, 0.44 (4), 41 (3); J, 0.28 (6), 78 (8); H, 0.21 (6),
94 (8); K, 0.21 (3), 96 (4). The observations show a continuation
of the reduction in polarization noted on IAUC 4337 and 4340. The
polarization is now close to the expected level of foreground
galactic interstellar polarization."
Visual magnitude estimates by R. H. McNaught, Coonabarabran,
N.S.W.: Mar. 22.60 UT, 4.1; 23.46, 4.1.
1987 March 24 (4351) Daniel W. E. Green
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