Central Bureau for Astronomical Telegrams
IAUC 3720: H 0139-68; SN IN NGC 7713; AM Her
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Read IAUC 3721
Circular No. 3720
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 617-864-5758
H 0139-68
J. Bailey, Anglo-Australian Observatory; and A. B. Giles,
D. J. Watts and J. G. Greenhill, University of Tasmania, report:
"The optical counterpart of H 0139-68 (IAUC 3649, 3658) has been observed
to show large circular polarization of its optical and near-infrared
radiation, confirming its identification as an AM-Her-type binary.
Observations with the Hatfield polarimeter on the Anglo-Australian
Telescope show that the circular polarization is negative for 30
percent of the cycle around the photometric maximum and positive for
the remainder of the cycle. Optical (white light) polarization ranges
from +15 to -9 percent. Infrared J-band polarization ranges from +10
to -2 percent. There is a minimum during the positive polarization
phase where the optical polarization drops to zero. This minimum is
not present in the infrared data."
N. Visvanathan and I. Tuohy, Mt. Stromlo and Siding Spring
Observatories, communicate: "Continuous linear polarization observations
in the V band, covering a full binary period, have been made for the
AM-Her-type object H 0139-68 (Visvanathan and Pickles 1982, Nature 298,
41) on June 19 and 21 at the 1.9-m telescope. On both occasions we
see two polarization spikes (about 10 percent) in each cycle: one spike
coincides with the sharp eclipse in the lightcurve of the object, and
the other occurs about 50 min later. The new results indicate that
cyclotron radiation is observed, not only from the main, asserting pole,
but also from the second pole of the magnetic white dwarf. Thus our
observations support a model of a two-pole magnetic white dwarf,
phase-locked in a short-period binary system, for the AM-Her object
H 0139-68.
SUPERNOVA IN NGC 7713
P. Seitzer and M. M. Philips, Cerro Tololo Interamerican
Observatory, confirm the identification of the supernova reported in NGC
7713 (IAUC 3717). A ccd prism spectrum taken with the 4-m telescope
shows a blue continuum with strong emission likely due to H alpha. Rough
photometric measurements made on Aug. 2.31 UT give B = 16.4 +/- 0.2,
B-V = +0.2 +/- 0.1.
AM HERCULIS
Visual magnitude estimates by M. Verdenet, Bourbon-Lancy,
France: June 23.9 UT, 13.3; 29.9, 14.4; July 7.9, 14.8; 8.9, 14.4.
1982 August 5 (3720) Brian G. Marsden
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