Strongly decelerated expansion of SN1979C

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 $M_{\mathrm{env}}\sim$ 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.

To appear in Astronomy & Astrophysics. 6 pages, 3 figures, uses aa.cls style file

References in corpus (3)

• The role of synchrotron self-absorption in the late radio emission of SN1993J
• Chandra X-Ray Point Sources, including Supernova 1979C, in the Spiral Galaxy M100
• Chandra and ASCA X-ray Observations of the Radio Supernova SN1979C IN NGC 4321

Cited by in corpus (5)

• Discovery of X-Ray Emission from Supernova 1970G with Chandra: Filling the Void between Supernovae and Supernova Remnants
• Late-time X-Ray, UV and Optical Monitoring of Supernova 1979C
• 1.6 GHz VLBI Observations of SN 1979C: almost-free expansion
• SN 1999ga: a low-luminosity linear type II supernova?
• Electron cooling and the connection between expansion and flux-density evolution in radio supernovae