STELLAR EXPLOSIONS

A comprehensive and Multi-facetted Study of Stellar Explosions and Eruptions using Radiation-Hydrodynamics and Time-Dependent Radiative Transfer Techniques

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 Obiettivo del progetto (Objective)

'Stellar explosions and giant outbursts from massive stars like Eta Carina constitute highly energetic events where radiation constitutes a critical dynamical ingredient as well as a fundamental probe of the event, opening to our eyes the Universe at large.

We propose to adapt, improve, and apply our radiation hydrodynamics and radiative transfer codes to model such astrophysical phenomena. Capitalizing on our former studies, we will model the spectra, light curves, and the polarization signatures of supernova (SN) explosions, interacting supernovae, as well as the giant outbursts of Luminous Blue Variables (LBVs). Our results will provide constraints on pre-SN massive star evolution and mass loss; stellar explosion mechanisms, energetics, and morphology; the identity of SN progenitors; the connection between SN explosions and SN impostors like LBVs; and finally, cosmology through the use of SNe for distance determinations in the Universe.

Some specific projects we will address are 1) Type II Plateau SNe and the Expanding Photosphere Method; 2) Type Ia SNe and the width-luminosity relation; 3) Type Ib/c SNe and the connection to X-ray-flashes/Gamma-ray-bursts; 4) interacting SNe such as the extremely luminous SN 2006gy or the low-mass SN 2008S; 5) shock breakout; 6) the potential explosive origin of LBV giant outbursts.

The multidisciplinary aspects of this proposal cover the nature and origin of stellar explosions and mass loss, which represent key questions of modern astrophysics. Our theoretical results will be confronted to observations, and will also motivate new programs on 8m-class telescopes. Based on an ongoing collaboration with researchers in the US (Hillier, Owocki) and in Israel (Livne), this proposal will assist with the reintegration of the applicant in Europe, and strengthen theoretical research on SN and massive stars in France.'

Introduzione (Teaser)

The study of massive star explosions can provide important insight into the evolution of the Universe and the distances among its objects. EU-funded scientists have developed and applied advanced models with exciting results.

Descrizione progetto (Article)

Scientists working on the EU-funded project STELLAR EXPLOSIONS developed improved models of explosion mechanisms and radiation dynamics. They applied them to probe the spectra, light curves and polarisation signatures of all types of supernovas (SNes), the largest explosions occurring in space, as well as to other explosive stellar events for exciting new descriptions of dynamics.

The key to success in modelling the mechanisms of explosions was in starting with physically consistent models of the progenitor star produced from the public stellar evolution code MESA-Star. Scientists then developed radiation hydrodynamics code, called V1D, to treat core collapse and stellar eruptions.

The pinnacle of project modelling was the development of CMFGEN, including all relevant processes for non-local thermodynamic equilibrium (non-LTE) and the time-dependence of radiative transfer in homologously expanding SNe ejecta. Ejecta are the remnants of the stars ejected when they explode. After billions of years of explosions, they provide important information about how the Universe came to be the way it is.

CMFGEN was expanded to include treatment of non-thermal processes as well, and has been tested against a variety of data.

STELLAR EXPLOSIONS uniquely combines three modelling codes (MESA, V1D and CMFGEN) for comprehensive dynamic descriptions of massive star explosions with unprecedented detail and interrelationships. In addition, CMFGEN enables detailed study of the non-LTE aspect of radiative transfer not possible with other available codes.Applications of the algorithms have provided groundbreaking information about all types of SNe explosions. Models of the ejecta have generated light curves and full polarised spectra for any SN type. Code development and application to observations have far exceeded original expectations, resulting in many publications in peer-reviewed scientific journals.

Overall, STELLAR EXPLOSIONS has delivered a suite of software tools for modelling the causes, mechanisms and effects of SNe explosions that will foster a powerful burst of experimental and theoretical investigations into some of the most important questions about our Universe.