ﻻ يوجد ملخص باللغة العربية
As the closest Type Ia supernova in decades, SN 2014J provides a unique opportunity for detailed investigation into observational signatures of the progenitor system and explosion mechanism in addition to burning product distribution. We present a late-time near-infrared spectral series from Gemini-N at $307-466$ days after the explosion. Following the $H$-band evolution probes the distribution of radioactive iron group elements, the extent of mixing, and presence of magnetic fields in the expanding ejecta. Comparing the isolated $1.6440$ $mu$m [Fe II] emission line with synthetic models shows consistency with a Chandrasekhar-mass white dwarf of $rho_c=0.7times10^9$ g cm${}^{-3}$ undergoing a delayed detonation. The ratio of the flux in the neighboring $1.54$ $mu$m emission feature to the flux in the $1.6440$ $mu$m feature shows evidence of some limited mixing of stable and radioactive iron group elements in the central regions. Additionally, the evolution of the $1.6440$ $mu$m line shows an intriguing asymmetry. When measuring line-width of this feature, the data show an increase in line width not seen in the evolution of the synthetic spectra, corresponding to $approx1{,}000$ km s${}^{-1}$, which could be caused by a localized transition to detonation producing asymmetric ionization in the ejecta. Using the difference in width between the different epochs, an asymmetric component in the central regions, corresponding to approximately the inner $2times10^{-4}$ of white dwarf mass suggests an off-center ignition of the initial explosion and hence of the kinematic center from the chemical center. Several additional models investigated, including a He detonation and a merger, have difficulty reproducing the features seen these spectra.
Aims. We present and analyse late-time observations of the type-Ib supernova with possible pre-supernova progenitor detection, iPTF13bvn, taken at $sim$300 days after the explosion, and discuss these in the context of constraints on the supernovas pr
We present very early, high-cadence photometric observations of the nearby Type Ia SN 2017cbv. The light curve is unique in that it has a blue bump during the first five days of observations in the U, B, and g bands, which is clearly resolved given o
We extend the range of validity of the ARTIS 3D radiative transfer code up to hundreds of days after explosion, when Type Ia supernovae are in their nebular phase. To achieve this, we add a non-local thermodynamic equilibrium (non-LTE) population and
We present near infrared (NIR) spectroscopy of the nearby supernova 2014J obtained $sim$450 d after explosion. We detect the [Ni II] 1.939 $mu$m line in the spectra indicating the presence of stable $^{58}$Ni in the ejecta. The stable nickel is not c
We constrain the properties of the progenitor system of the highly reddened Type Ia supernova (SN) 2014J in Messier 82 (M82; d ~ 3.5 Mpc). We determine the SN location using Keck-II K-band adaptive optics images, and we find no evidence for flux from