Lagrangian perturbation theory for rotating magnetic stars
| dc.creator | Glampedakis, Kostas | |
| dc.creator | Andersson, Nils | |
| dc.date | 2007-02-14 | |
| dc.date.accessioned | 2026-07-07T10:21:47Z | |
| dc.date.available | 2026-07-07T10:21:47Z | |
| dc.description | Motivated by the possibility of radiation driven instabilities in rotating magnetic stars, we study the stability properties of general linear perturbations of a stationary and axisymmetric, infinitely conducting perfect fluid configuration threaded by a magnetic field and surrounded by vacuum. We develop a Lagrangian perturbation framework which enables us to formulate a strict stability criterion based on the notion of a canonical energy (a functional of the fluid displacement $ξ$ and its first time derivative). For any given choice of $\{ξ,\partial_t ξ\} $, the sign of the canonical energy determines whether the configuration is stable or not at the linear level. Our analysis provides the first complete description of the stability problem for a magnetic star, allowing for both rotation and the presence of a magnetic field in the exterior vacuum region. A key feature of the Lagrangian formulation is the existence of so-called `trivial' fluid displacements, which do not represent true physical perturbations. In order for the stability criterion to make rigorous sense one has to isolate these trivials and consider only the physical `canonical' displacements. We discuss this problem and formulate a condition which must be satisfied by all canonical displacements. Having obtained a well-defined stability criterion we provide examples which indicate that the magnetic field has a stabilising effect on radiation driven instabilities. | |
| dc.description | 16 pages, accepted for publication in MNRAS | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0702382 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0702382 | |
| dc.identifier | Mon.Not.Roy.Astron.Soc.377:630-644,2007 | |
| dc.identifier | doi:10.1111/j.1365-2966.2007.11625.x | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/175291 | |
| dc.subject | Astrophysics | |
| dc.title | Lagrangian perturbation theory for rotating magnetic stars | |
| dc.type | text |