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2012 (English)In: ASTROPHYSICAL JOURNAL LETTERS, ISSN 2041-8205, Vol. 750, no 2, L40- p.Article in journal (Refereed) Published
Abstract [en]

We report on Expanded Very Large Array observations of the Type IIb supernova 2011dh, performed over the first 100 days of its evolution and spanning 1-40 GHz in frequency. The radio emission is well described by the self-similar propagation of a spherical shockwave, generated as the supernova ejecta interact with the local circumstellar environment. Modeling this emission with a standard synchrotron self-absorption (SSA) model gives an average expansion velocity of v approximate to 0.1c, supporting the classification of the progenitor as a compact star (R-star approximate to 10(11) cm). We find that the circumstellar density is consistent with a rho proportional to r(-2) profile. We determine that the progenitor shed mass at a constant rate of approximate to 3 x 10(-5) M-circle dot yr(-1), assuming a wind velocity of 1000 km s(-1) (values appropriate for a Wolf-Rayet star), or approximate to 7 x 10(-7) M-circle dot yr(-1) assuming 20 km s(-1) (appropriate for a yellow supergiant [YSG] star). Both values of the mass-loss rate assume a converted fraction of kinetic to magnetic energy density of epsilon(B) = 0.1. Although optical imaging shows the presence of a YSG, the rapid optical evolution and fast expansion argue that the progenitor is a more compact star-perhaps a companion to the YSG. Furthermore, the excellent agreement of the radio properties of SN 2011dh with the SSA model implies that any YSG companion is likely in a wide, non-interacting orbit.

Place, publisher, year, edition, pages
2012. Vol. 750, no 2, L40- p.
Keyword [en]
supernovae: individual (SN 2011dh)
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-80104DOI: 10.1088/2041-8205/750/2/L40ISI: 000303448700014OAI: diva2:553403


Available from: 2012-09-19 Created: 2012-09-12 Last updated: 2012-09-19Bibliographically approved

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Fransson, Claes
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Department of AstronomyThe Oskar Klein Centre for Cosmo Particle Physics (OKC)
Astronomy, Astrophysics and Cosmology

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