0000000000133221
AUTHOR
Corrado Trigilio
Discovery of shell-like radio-structure in SN1993J
The radio-luminous supernova SN 1993J in M81 offers an unprecedented opportunity to study with high linear resolution the details of the growth of a supernova radio structure by means of the VLBI technique.
Deceleration in the Expansion of SN 1993J
A rarity among supernova, SN 1993J in M81 can be studied with high spatial resolution. Its radio power and distance permit VLBI observations to monitor the expansion of its angular structure. This radio structure was previously revealed to be shell-like and to be undergoing a self-similar expansion at a constant rate. From VLBI observations at the wavelengths of 3.6 and 6 cm in the period 6 to 42 months after explosion, we have discovered that the expansion is decelerating. Our measurement of this deceleration yields estimates of the density profiles of the supernova ejecta and circumstellar material in standard supernova explosion models.
Expansion of SN 1993J: New λλ6 and 13 cm images
Abstract Radio supernovae are rare events among supernovae, usually taking place in distant galaxies. In recent years, great progress has been made in the study of radio supernovae with high angular resolution, due to advances in the VLBI technique and to the lucky occurrence of the powerful supernova SN 1993J in M81 only 3.6 Mpc distant. Its spatial structure has been unveiled and its expansion rate determined at 3.6 cm. Here we present new preliminary VLBI results on the expansion of this supernova at 6 and 13 cm. We resolve the shell at both wavelengths. The size estimates at 6 cm indicate a lower expansion rate than previously estimated. This may be the first evidence of deceleration.
A decade of SN 1993J : discovery of radio wavelength effects in the expansion rate
We studied the growth of the shell-like radio structure of supernova SN 1993J in M 81 from September 1993 to October 2003 with very-long-baseline interferometry (VLBI) observations at the wavelengths of 3.6, 6, and 18 cm. We developed a method to accurately determine the outer radius (R) of any circularly symmetric compact radio structure such as SN 1993J. The source structure of SN 1993J remains circularly symmetric (with deviations from circularity under 2%) over almost 4000 days. We characterize the decelerated expansion of SN 1993J until approximately day 1500 after explosion with an expansion parameter m = 0.845 ± 0.005 (R ∝ tm). However, from that day onwards the expansion differs whe…
Expansion of SN 1993J
A sequence of images from very long baseline interferometry shows that the young radio supernova SN 1993J is expanding with circular symmetry. However, the circularly symmetric images show emission asymmetries. A scenario in which freely expanding supernova ejecta shock mostly isotropic circumstellar material is strongly favored. The sequence of images constitutes the first “movie” of a radio supernova.