ﻻ يوجد ملخص باللغة العربية
We undertake a statistical analysis of the radial abundance distributions in the Galactic disk within a theoretical framework for Galactic chemical evolution which incorporates the influence of spiral arms. 1) The mean mass of oxygen ejected per core-collapse SNe (CC SNe) event (which are concentrated within spiral arms) is $sim$0.27 M$_{odot}$; 2) the mean mass of iron ejected by `tardy Type Ia SNe (SNeIa; progenitors of whom are older/longer-lived stars with ages $simgt$100 Myr and up to several Gyr, which do not concentrate within spiral arms) is $sim$0.58 M$_{odot}$; 3) the upper mass of iron ejected by prompt SNeIa (SNe whose progenitors are younger/shorter-lived stars with ages $simlt$100 Myr, which are concentrated within spiral arms) is $leq$0.23 M$_{odot}$ per event; 4) the corresponding mean mass of iron produced by CC SNe is $leq$0.04 M$_{odot}$ per event; (v) short-lived SNe (core-collapse or prompt SNeIa) supply $sim$85% of the Galactic disks iron. The inferred low mean mass of oxygen ejected per CC SNe event implies a low upper mass limit for the corresponding progenitors of $sim$23 M$_{odot}$, otherwise the Galactic disk would be overabundant in oxygen. The low mean mass of iron ejected by prompt SNeIa, relative to the mass produced by tardy SNeIa ($sim$2.5 times lower), prejudices the idea that both sub-populations of SNeIa have the same physical nature. We suggest that, perhaps, prompt SNeIa are more akin to CC SNe, and discuss the implications of such a suggestion.
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
We searched through roughly 12 years of archival survey data acquired by the Katzman Automatic Imaging Telescope (KAIT) as part of the Lick Observatory Supernova Search (LOSS) in order to detect or place limits on possible progenitor outbursts of Typ
With the same method as used previously, we investigate neutrino-driven explosions of a larger sample of blue supergiant models. The larger sample includes three new presupernova stars. The results are compared with light-curve observations of the pe
Using HST photometry, we age-date 59 supernova remnants (SNRs) in the spiral galaxy M31 and use these ages to estimate zero-age main sequence masses (MZAMS) for their progenitors. To accomplish this, we create color-magnitude diagrams (CMDs) and use
Feedback from supernovae is an essential aspect of galaxy formation. In order to improve subgrid models of feedback we perform a series of numerical experiments to investigate how supernova explosions power galactic winds. We use the Flash hydrodynam