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| Content Provider | EDP Sciences |
|---|---|
| Author | C. Sauty |
| Abstract | L'éjection continue de plasma autour d'objets massifs est un phénomène largement répandu en astrophysique, que ce soit sous la forme du vent solaire, de vents stellaires, de jets d'étoiles en formation, de jets stellaires autour d'objets compacts ou de jets extra-galactiques. Cette zoologie diversifiée fait pourtant l'objet d'un commun effort de modélisation. Le but de cette revue est d'abord de présenter qualitativement le développement, depuis leur origine, des diverses théories de vents (Partie 1) et l'inter disciplinarité dans ce domaine. Il s'agit d'une énumération, plus ou moins exhaustive, des idées proposées pour expliquer l'accélération et la morphologie des vents et des jets, accompagnée d'une présentation sommaire des aspects observationnels. Cette partie s'abstient de tout aspect faisant appel au formalisme mathématique. Ces écoulements peuvent être décrits, au moins partiellement, en résolvant les équations magnétohydrodynamiques, axisymétriques et stationnaires. Ce formalisme, à la base de la plupart des théories, est exposé dans la Partie 2. Il permet d'introduire quantitativement les intégrales premières qu'un tel système possède. Ces dernières sont amenées à jouer un rôle important dans la compréhension des phénomènes d'accélération ou de collimation, en particulier le taux de perte de masse, le taux de perte de moment angulaire ou l'énergie du rotateur magnétique. La difficulté de modélisation réside dans l'existence de points critiques, propres aux équations non linéaires, qu'il faut franchir. La nature physique et la localisation de ces points critiques fait l'objet d'un débat important car ils sont la clef de voute de la résolution. Nous introduisons donc la notion de topologie des points critiques (Parties 3 et 4) en allant du cas le plus simple, hydrodynamique à symétrie sphérique, aux cas plus complexes, magnétohydrodynamiques et axisymétriques. Une attention particulière est donnée aux modèles auto-similaires qui, par leur approche semi-analytique, permettent de dégager des idées simples sur le problème. A la lumière de ces notions, nous pouvons confronter plus quantitativement que dans la Partie 1, les résultats obtenus par les différents modèles sur la morphologie des écoulements. Nous montrons ainsi que la collimation magnétique des vents en jets est un phénomène largement attendu d'un point de vue théorique. Cependant, si la collimation peut être conique, parabolique ou cylindrique (Partie 4), c'est la collimation cylindrique qui semble la configuration la plus favorable. La forme de la collimation peut être alors utilisée comme outil de prédiction sur les conditions physiques dans l'écoulement et à sa source. |
| Ending Page | 599 |
| Starting Page | 459 |
| Page Count | 141 |
| File Format | HTM / HTML PDF |
| ISSN | 00034169 |
| Alternate Webpage(s) | https://www.annphys.org/articles/anphys/abs/1994/05/anphys_1994__19_5_459_0/anphys_1994__19_5_459_0.html |
| e-ISSN | 12864838 |
| Issue Number | 5 |
| Journal | Annales de Physique |
| Volume Number | 19 |
| DOI | 10.1051/anphys:01994001905045900 |
| Language | French |
| Publisher | EDP Sciences |
| Publisher Date | 1994-01-01 |
| Access Restriction | Subscribed |
| Rights Holder | © EDP Sciences, 1994 |
| Subject Keyword | active galaxies / astrophysical jets / astrophysical plasma / galactic nuclei / pre main sequence stars / quasars / reviews / solar wind / stellar winds / winds / jets / plasma outflows / solar wind / stellar wind / young stellar objects / compact stellar objects / extra galactic jets / active galactic nuclei / quasars / acceleration / morphologies / macroscopic properties / outflows / magnetohydrodynamic equations / free integrals / collimation / critical points / nonlinear equations / hydrodynamic case / spherically symmetric case / axisymmetric cases Astrophysical hydromagnetics and plasmas Mass transfer Galactic structure, content and morphology Active and peculiar galaxies Quasars Reviews and tutorial papers resource letters Pre main sequence stars Other types of variable and peculiar stars Solar wind plasma |
| Content Type | Text |
| Resource Type | Article |
| Subject | Physics and Astronomy |
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