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Date: Tue, 8 Jun 93 12:23:57 +0900 From: nomoto@apsun1.astron.s.u-tokyo.ac.jp Subject: pulsar? Date: Mon, 7 Jun 93 22:06:04 GMT From: wheel@astro.as.utexas.edu (Craig Wheeler) Subject: pulsar? We have been puzzling over the photometric behaviour of SN 1993J. It is distinctly different than SN 1987A. After the second, radioactive peak, SN 1987A was almost flat in U, but declined at distinctly steeper slopes for redder bands, BVRI. Although the timescales are accelerated because of the lower mass of the ejecta, there is a general concensus that SN 1993J has undergone a similar radioactive peak. After this peak, SN 1993J has shown a tendency for the rate of decline to decrease in all bands. If anything the rate of decline is less in the redder bands, just the opposite of SN 1987A. One can imagine that all the bands, including the bolometric light curve (Schmidt et al, submitted to Nature, and Alak Ray et al. presented in Xian) are approaching an asymptote. At the risk of causing another great pulsar panic, the naive interpretation of this is that there is a buried source of nearly constant luminosity, the clue for which we have searched without success for 6 years in SN 1987A. Our light curve models show that a constant luminosity of 10^41 erg/s in addition to radioactive decay is compatible with the current observations. If this is a pulsar with 10^12 Gauss, powered by a simple dipole mechanism, then it corresponds to a period of 5 ms. Observers in all wavelength bands should monitor SN 1993J closely to confirm or deny this conjecture, and the observed broad-band colors throughout the range UBVRI should especially be closely monitored. Craig Wheeler
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