Abstract:
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
(∼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 Mꙩ radioactive ⁵⁶Ni is produced and roughly 4.4 Mꙩ material is ejected during
this explosion with liberated energy ∼15 × 10⁵¹ 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 ⁵⁶Ni 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 ≳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 Mꙩ yr⁻¹ , which is consistent with the results obtained
for other Type Ibc SNe bright at radio frequencies.
