Résumé / Abstract Seminaire_GReCO

"The magnetic wake of planets and small bodies in a pulsar's wind"

Fabrice Mottez
Lab. Univers et Théories (LUTH), Obs. Paris-Meudon-Nancay (Meudon, France)

We investigate the electromagnetic interaction of a relativistic and magnetized stellar wind with a planet or a smaller body in orbit around a pulsar. This may be relevant to objects such as PSR B1257+12 and PSR B1620-26 that are expected to hold a planetary system, or to other pulsars with suspected asteroids or comets. Most models predict that, albeit highly relativistic, pulsar winds are slower than Alfvén waves (Alfvén waves mainly propagate magnetic perturbations). In that case, a pair of stationary Alfvén waves, called Alfvén wings (AW), is expected to form on the sides of the planet. They are the magnetic wake of the body into the plasma flow, like the wake of a boat left into the sea (with a similar shape). The theory of Alfvén wings was initially developed in the context of the Io-Jupiter interaction. We have extended it to relativistic winds, and we have studied the possible consequences that could be relevant for observations : possible radio emissions from pulsar's planets (could we observe them with the next generation of radio-telescopes ?), and a magnetic force configuration that can deeply modify the orbit of the smaller bodies (asteroids, comets). Their influence on the orbit of small bodies might have important consequences on the scenarios of pulsar's planet formation from debris of the supernova.

lundi 22 octobre 2012 - 14:00
Salle des séminaires François Arago,
Institut d'Astrophysique de Paris

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