NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-08-20 T18:30:26 PDT
Help | Comment | NED Home

For refcode 2003ApJ...591..301B:
Retrieve 2 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
2003ApJ...591..301B SN 1979C VLBI: 22 Years of Almost Free Expansion Bartel, Norbert; Bietenholz, Michael F. Abstract. VLBI measurements of the size of SN 1979C in M100 (NGC 4321) in the Virgo Cluster, from t=3.7 yr after the explosion, show an expansion ~t^m^, which is, with m=0.95+/-0.03, almost consistent with being free for 22 years. The last size measurement, at t=22 yr, may indicate for the first time a change of the expansion of the supernova and suggests, as an alternative, free expansion ~t^m^ with m=1.00+/-0.05 up to t_b_~17 yr followed by marginally significant deceleration with m=0.74+/-0.17. The possible deceleration could be weaker within the errors for t_b_<17 yr or stronger for t_b_>17 yr. With the assumption for the density profile of the circumstellar medium (CSM) of {rho}_CSM_~r^-s^, we derive a model-dependent value of s=1.95^+0.10^_-0.05_ up to a distance from the progenitor, r=r_b_, that corresponds to t_b_~17 yr, which changes to s<~1.5 for r>r_b_. For a kinetic energy of the shocked ejecta and CSM shells of E_kin_=10^51^ ergs, our results require a mass loss to wind velocity ratio for the progenitor of M^dot^_w_/w~1 x 10^-5^ M_sun_ yr^-1^ per w=10 km s^-1^, an order of magnitude smaller than estimated from radio light-curve fitting. The swept-up mass at t=22 yr is then M_sw_=0.3 M_sun_ and the inferred mass of the shocked ejecta M_shock-ej_=2^+4^_-1_ M_sun_. Our last observations give an image of a barely resolved source with a first hint on the structure of the supernova, consistent with being circular within 9% and possibly center filled. The expanding shock front method (ESM) of combining the transverse radio expansion velocities with the radial optical velocities gives direct distance estimates to M100, with standard errors of D=16.5+/-2.5 to 19.8+/-3.0 Mpc, depending on whether the supernova has a bright center or is a shell without such a center. These estimates are comparable with those from Cepheid observations (e.g., 16.1 and 15.2 Mpc). Keywords: Cosmology: Distance Scale, Galaxies: Distances and Redshifts, Galaxies: Individual: Messier Number: M100, Radio Continuum: Stars, Stars: Supernovae: Individual: Alphanumeric: SN 1979C
Retrieve 2 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home