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Strongly decelerated expansion of SN1979C

J. M. Marcaide·M. A. Perez-Torres·E. Ros·A. Alberdi·P. J. Diamond·J. C. Guirado·L. Lara·S. D. Van Dyk·K. W. Weiler
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Abstract

We observed SN1979C in M100 on 4 June 1999, about twenty years after explosion, with a very sensitive four-antenna VLBI array at the wavelength of 18cm. The distance to M100 and the expansion velocities are such that the supernova cannot be fully resolved by our Earth-wide array. Model-dependent sizes for the source have been determined and compared with previous results. We conclude that the supernova shock was initially in free expansion for 6 +/- 2 yrs and then experienced a very strong deceleration. The onset of deceleration took place a few years before the abrupt trend change in the integrated radio flux density curves. We estimate the shocked swept-up mass to be about 1.6 solar masses, assuming a standard density profile for the CSM. Such a swept-up mass for SN1979C suggests a mass of the hydrogen-rich envelope ejected at explosion no larger than $M_{\rm env} \sim$ 0.9 solar masses. If SN1979C originated in a binary star the low value of M_env suggests that the companion of the progenitor star stripped off most of the hydrogen-rich envelope mass of the presupernova star prior to the explosion.

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J. M. Marcaide, M. A. Perez-Torres, E. Ros, A. Alberdi, P. J. Diamond, J. C. Guirado, L. Lara, S. D. Van Dyk, K. W. Weiler. 2002-01-15. Strongly decelerated expansion of SN1979C. https://doi.org/10.1051/0004-6361%3A20011794

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