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Date: Tue, 26 Oct 93 15:55:30 EDT
From: Kurt w. Weiler <kweiler@shimmer.nrl.navy.mil>
Subject: Abstract
26 October 1993
Dear Colleague:
I have prepared a short paper on the early radio emission from
SN1993J for the proceedings of the 34th Herstmonceux Conference on
"Circumstellar Media in the Late Stages of Stellar Evolution." If you
would like a copy, please let me know and I can e-mail you two
PostScript files -- the first containing the text and the second
containing the single figure.
Regards,
Kurt Weiler
THE EARLY RADIO EMISSION FROM SN1993J
Kurt W. Weiler1, Schuyler D. Van Dyk1,2, Richard A. Sramek3, Nino
Panagia4,5, and Michael P. Rupen3
1Remote Sensing Division, Code 7215, Naval Research Laboratory,
Washington, DC, 20375-5351, USA
2Naval Research Laboratory/NRC Cooperative Research Associate
3National Radio Astronomy Observatory, P.O. Box O, Socorro, NM
87801, USA
4Space Telescope Science Institute, 3700 San Martin Drive, Baltimore,
MD 21218, USA; affiliated with the Astrophysics Division, Space
Science Department of ESA
5University of Catania, Italy
ABSTRACT
After initial upper limits on the 3.6 and 2 cm radio emission
from SN1993J established by the Very Large Array (VLA) on 1993
March 31 only three days after optical discovery, the supernova was
first detected in the radio range with a flux density of 0.8 mJy at 1.3
cm wavelength on 1993 April 2. This makes it the earliest epoch and
highest frequency that any Type II supernova has ever been detected
in the radio. Since that time, regular monitoring has been done with
the VLA at 1.3, 2, 3.6, 6, and 20 cm wavelengths to obtain the most
detailed, multifrequency radio light curves ever established for any
supernova. First analysis of this initial data set reveals that while the
evolution of the radio emission from SN1993J is regular in both time
and frequency, it is not well described by the previously successful
modified Chevalier model. A model in which the external and
internal absorption obey the same power law evolution with time and
with a slower temporal decline rate than predicted by the Chevalier
model gives a good description of the data.
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