SN 2007uy-metamorphosis of an aspheric Type Ib explosion

• The supernovae (SNe) of Type Ibc are rare and the detailed characteristics of these explosions have been studied only for a few events. Unlike Type II SNe, the progenitors of Type Ibc have never been detected in pre-explosion images. So, to understand the nature of their progenitors and the characteristics of the explosions, investigation of proximate events is necessary. Here we present the results of multiwavelength observations of Type Ib SN 2007uy in the nearby (similar to 29.5 Mpc) galaxy NGC 2770. Analysis of the photometric observations revealed this explosion as an energetic event with peak absolute R-band magnitude -18.5 +/- 0.16, which is about 1 mag brighter than the mean value (-17.6 +/- 0.6) derived for well observed Type Ibc events. The SN is highly extinguished, E(B - V) = 0.63 +/- 0.15 mag, mainly due to foreground material present in the host galaxy. From optical light curve modelling we determine that about 0.3 M-circle dot radioactive Ni-56 is produced and roughly 4.4 M-circle dot material is ejected during this explosion with liberated energy similar to 15 x 10(51) erg, indicating the event to be an energetic one. Through optical spectroscopy, we have noticed a clear aspheric evolution of several line-forming regions, but no dependency of asymmetry is seen on the distribution of Ni-56 inside the ejecta. The SN shock interaction with the circumstellar material is clearly noticeable in radio follow-up, presenting a synchrotron self-absorption dominated light curve with a contribution of free-free absorption during the early phases. Assuming a Wolf-Rayet (WR) star, with wind velocity greater than or similar to 10(3) km s(- 1), as a progenitor, we derive a lower limit to the mass-loss rate inferred from the radio data as M 2.4 10(-5) M-circle dot yr(-1), which is consistent with the results obtained for other Type Ibc SNe bright at radio frequencies.

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Nyckelord

supernovae: general

supernovae: individual: SN 2007uy

galaxies: individual: NGC 2770

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