MPIfR: Eduardo Ros

Strongly decelerated expansion of SN 1979C,
J.M. Marcaide, M.A. Pérez-Torres, E. Ros, A. Alberdi, P.J. Diamond, J.C. Guirado, L. Lara, S.D. Van Dyk, K.W. Weiler
Astronomy & Astrophysics, 384:408-413 (2002)
- Abstract We observed SN 1979C in M100 on 4 June 1999, about twenty years after explosion, with a very sensitive four-antenna VLBI array at the wavelength of 18 cm. 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. The strong deceleration suggests that the shock-processed stellar wind mass must be comparable to the envelope mass ejected by the progenitor. Since both masses are relatively small (around 1.6 solar masses), our result favors a core collapse supernova that originated in a binary star scenario.