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Enveloppes circumstellaires des étoiles chaudes actives: modélisation et observations à haute résolution angulaire du phénomène Be et B[e]

Jamal Bittar
Abstract : The main objective of this PhD thesis was to add new elements to the knowledge of hot active stars and in particular the study of the Be and B[e] phenomena. To this aim, I have studied the différent characteristics of these objects and tried to highlight the différence between classical Be stars and B[e] stars. This allowed me to model the main characteristics thanks to the development of a radiative transfer code by Stee & Araùjo (1994). Based on this model, I created the code SIMECA (SIMUlation pour Etoiles Chaudes Actives) which I then adapted to the special case of a B[e] star modelled as a classical Be star surrounded by a circumstellar dust envelope. I solved the radiative transfer problem in the dust using the code developed by Lopez et al. (1995) based on a Monte Carlo method. I modified this code, which had been developed originally for AGB stars, and replaced the central blackbody by a Be star with its circumstellar envelope of gas. In order to test the validity of this model, I compared the results of the numerical simulations with observations. Due to the coming of the optical inteferometry at the VLT with the near infrared focal instrument AMBER, I extended the theoretical observables calculated by SIMECA to this wavelength range and in particular by simulating the line Bry at 21655 Â. This allowed me to make two proposals, one for the classical Be stars and the other for the B[e] stars, that was accepted as part of the guaranteed time allocated to the AMBER Consortium. To accomplish this, I performed an exhaustive study of the effects of different free parameters on the theoretical observables calculated by SIMECA. Finally the result of this work is the creation of a self consistent code SIMECA accessible with a friendly user interface and that allows the simulation of the principle caracteristics of the Be phenomenon together with a physical model that describes the circumstellar environment of the B[e] stars. These codes are available for the whole stellar physics community.
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https://tel.archives-ouvertes.fr/tel-00006962
Contributor : Jamal Bittar <>
Submitted on : Sunday, September 26, 2004 - 11:02:29 AM
Last modification on : Wednesday, June 1, 2016 - 11:13:20 PM
Long-term archiving on: : Monday, September 6, 2010 - 11:31:13 AM

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  • HAL Id : tel-00006962, version 1

Citation

Jamal Bittar. Enveloppes circumstellaires des étoiles chaudes actives: modélisation et observations à haute résolution angulaire du phénomène Be et B[e]. Astrophysique [astro-ph]. Université Paul Sabatier - Toulouse III, 2001. Français. ⟨tel-00006962⟩

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