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Published March 3, 2002 | Published + Submitted
Journal Article Open

Strongly decelerated expansion of SN 1979C


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 λ18 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. We estimate the shocked swept-up mass to be M_(sw) ~ 1.6 M_⊙, assuming a standard density profile for the CSM. Such a swept-up mass for SN 1979C suggests a mass of the hydrogen-rich envelope ejected at explosion no larger than M_(env) ~ 0.9 M_⊙. If SN 1979C 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.

Additional Information

© 2002 ESO. Received: 20 July 2001. Accepted: 11 December 2001. We are grateful to A. Kraus for the help provided during the observations and the flux density measurements on PKS B1157+156. This work has been partially supported by the Spanish DGICYT Grants No. PB96-0782 and PB97-1164. NRAO is operated under license by Associated Universities, Inc., under cooperative agreement with NSF. We acknowledge support from the European Commission's TMR-LSF programme, Contract No. ERBFMGEST950012. JMM is grateful to the Max-Planck Institut für Radioastronomie for the support received for this research during his visit. KWW wishes to thank the Office of Naval Research for the 6.1 funding supporting this work.

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Published - aah3030.pdf

Submitted - 0201206.pdf


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August 19, 2023
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