Accreting white dwarf models for the type I supernovae. IV The optical spectrum of a carbon-deflagration supernova

Branch, David; Doggett, J. B.; Nomoto, Ken’ichi; Thielemann, Friedrich‐Karl

doi:10.1086/163329

Cited by 134 publications

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“…4 shows the op tical spectrum of SN 1981b with lines of O, Mg, Si, S, Ca, and Co. For comparison a "synthetic" spectrum is shown, calcu lated with the abundances of Fig. 3 and the hydrodynamic behaviour of the cor responding model (Branch et al 1985). of SN 1981b (upper curve (Branch et al 1985), shifted for ease of comparison.…”

Section: Observationsmentioning

confidence: 99%

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Supernovae and their Progenitors

Thielemann¹

1985

Europhys. News

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Section: Observationsmentioning

confidence: 99%

“…3 and the hydrodynamic behaviour of the cor responding model (Branch et al 1985). of SN 1981b (upper curve (Branch et al 1985), shifted for ease of comparison.…”

Section: Observationsmentioning

confidence: 99%

Supernovae and their Progenitors

Thielemann¹

1985

Europhys. News

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“…Historically, one-dimensional (ID) or spherically symmetric explosion models have been used to synthesize emergent spectra in good agreement with observed ones (Branch et al, 1985;Nugent et al, 1995;Mitchell et al, 2001). But new data and new computational technologies have led to a new class of muItidimensfcmoZ explosion models, making the need for multidimensional spectrum synthesis more pressing.…”

Section: Hamentioning

confidence: 99%

“…Despite this, many ID explosion models result in synthetic spectra consistent with observed ones (notably, deflagration model W7 - Nomoto et al, 1984;Branch et al, 1985). Still, recent advances in computer science permit explosion modellers to try to include the 3D nature of the flame front in their simulations, in an eflort to simulate more physically the explosions of white dwarfs (Khokhlov, 2000;Reinecke et al, 2002;Gamezo et al, 2003, -all deflagrations).…”

Section: Hapter 3 Line Form Ation In 3d Sn M Odelsmentioning

confidence: 99%

Synthetic spectrum methods for three-dimensional supernova models

Thomas

2004

Cosmic Explosions in Three Dimensions

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“…To simulate and understand the processes involved in SN Ia envelopes different numerical approaches have been developed to describe the radiative transfer and the evolution of the light curves: based on a variety of approaches and involving different levels of complexity models have been developed by several groups (Branch et al 1985;Eastman & Pinto 1993;Höflich et al 1995;Nugent et al 1995a;Pauldrach et al 1996;Nugent et al 1997;Lentz et al 2001;Höflich 2005;Stehle et al 2005;Sauer et al 2006; Baron et al 2006;Kasen et al 2006). However, with a view to the purpose of the specific codes various simplifications have been applied in the past, as not all approaches were intended to provide a comprehensive description of the timedependent spectra, including the detailed statistical equilibrium of all relevant elements.…”

Section: Introductionmentioning

confidence: 99%

Non-LTE models for synthetic spectra of type Ia supernovae

Pauldrach

Hoffmann

Hultzsch

2014

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Context. In type Ia supernova (SN Ia) envelopes a huge number of lines of different elements overlap within their thermal Doppler widths, and this problem is exacerbated by the circumstance that up to 20% of these lines can have a line optical depth greater than 1. The stagnation of the lambda iteration in such optically thick cases is one of the fundamental physical problems inherent in the iterative solution of the non-LTE problem, and the failure of a lambda iteration to converge is a point of crucial importance whose physical significance must be understood completely. Aims. We discuss a general problem related to radiative transfer under the physical conditions of supernova ejecta that involves a failure of the usual non-LTE iteration scheme to converge when multiple strong opacities belonging to different physical transitions come together, similar to the well-known situation where convergence is impaired even when only a single process attains large optical depths. The convergence problem is independent of the chosen frequency and depth grid spacing, independent of whether the radiative transfer is solved in the comoving or observer's frame, and independent of whether a common complete-linearization scheme or a conventional accelerated lambda iteration (ALI) is used. The problem appears when all millions of line transitions required for a realistic description of SN Ia envelopes are treated in the frame of a comprehensive non-LTE model. The only way out of this problem is a complete-linearization approach which considers all ions of all elements simultaneously, or an adequate generalization of the established ALI technique which accounts for the mutual interaction of the strong spectral lines of different elements and which thereby unfreezes the "stuck" state of the iteration. Methods. The physics of the atmospheres of SN Ia are strongly affected by the high-velocity expansion of the ejecta, dominating the formation of the spectra at all wavelength ranges. Thus, hydrodynamic explosion models and realistic model atmospheres that take into account the strong deviation from local thermodynamic equilibrium are necessary for the synthesis and analysis of the spectra. In this regard one of the biggest challenges we have found in the modeling of the radiative transfer in SN Ia is the fact that the radiative energy in the UV has to be transferred only via spectral lines into the optical regime in order to be able to leave the ejecta. However, convergence of the model toward a state where this is possible is impaired when using the standard procedures. We report on improvements in our approach of computing synthetic spectra for SN Ia with respect to (i) an improved and sophisticated treatment of many thousands of strong lines that interact intricately with the "pseudo-continuum" formed entirely by Doppler-shifted spectral lines, (ii) an improved and expanded atomic database, and (iii) the inclusion of energy deposition within the ejecta arising from the radioactive decay of mostly 56 Ni and 56 Co. Results....

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Accreting white dwarf models for the type I supernovae. IV The optical spectrum of a carbon-deflagration supernova

Cited by 134 publications

References 0 publications

Supernovae and their Progenitors

Supernovae and their Progenitors

Synthetic spectrum methods for three-dimensional supernova models

Non-LTE models for synthetic spectra of type Ia supernovae

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