212 research outputs found
Prospects for SNIa Explosion Mechanism Identification Through Supernova Remnants
We present the first results from an ongoing work aimed to use supernovae
remnants to discriminate among different type Ia supernovae explosion models.
We have computed the hydrodynamic interaction of supernova ejecta with the
interstellar medium, obtaining the evolution of the density, temperature and
ionization structure of the remnant. We have used ejecta profiles obtained from
1D hydrodynamic calculations of the different explosion mechanisms that are
currently under debate. We have analyzed the best indicators that allow to
discriminate among the different explosion mechanisms, taking into account the
diversity of scenarios proposed for the presupernova evolution of the binary
system, and the uncertain amount of electron heating in collisionless shocks.Comment: 4 pages, 3 figures. Proceedings of the ESO/MPA/MPE Workshop 'From
Twilight to Highlight', the Physics of Supernovae. Garching July 29 - 31,
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SNR-calibrated Type Ia supernova models
Current Type Ia supernova (SN Ia) models can reproduce most visible+IR + UV observations. In the X-ray band, the determination of elemental abundance ratios in supernova remnants (SNRs) through their spectra has reached enough precision to constrain SN Ia models. MartĂnez-RodrĂguez et al have shown that the Ca/S mass ratio in SNRs cannot be reproduced with the standard nuclear reaction rates for a wide variety of SN Ia models, and suggested that the 12C+16O reaction rate could be overestimated by a factor as high as ten. We show that the same Ca/S ratio can be obtained by simultaneously varying the rates of the reactions 12C + 16O, 12C + 12C, 16O + 16O, and 16O(Âż, a)12C within the reported uncertainties. We also show that the yields of the main products of SN Ia nucleosynthesis do not depend on the details of which rates are modified, but can be parametrized by an observational quantity such as Ca/S. Using this SNR-calibrated approach, we then proceed to compute a new set of SN Ia models and nucleosynthesis for both Chandrasekhar and sub-Chandrasekhar mass progenitors with a 1D hydrodynamics and nucleosynthesis code. We discuss the nucleosynthesis of the models as a function of progenitor metallicity, mass, and deflagration-to-detonation transition density. The yields of each model are almost independent on the reaction rates modified for a common Ca/S ratio.Peer ReviewedPostprint (author's final draft
Time-Resolved Spectroscopy with SDSS
We present a brief technical outline of the newly-formed 'Detection of
Spectroscopic Differences over Time' (DS/DT) project. Our collaboration is
using the individual exposures from the SDSS spectroscopic archive to produce a
uniformly-processed set of time-resolved spectra. Here we provide an overview
of the properties and processing of the available data, and highlight the wide
range of time baselines present in the archive.Comment: 2 pages, to appear in proc. IAU Symp. 285, "New Horizons in Time
Domain Astronomy", Oxford, Sept. 201
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