EDP Sciences
Free access
Issue
A&A
Volume 410, Number 3, November II 2003
Page(s) L33 - L36
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20031459


A&A 410, L33-L36 (2003)
DOI: 10.1051/0004-6361:20031459

Letter

Mean-field dynamo action in protoneutron stars

A. Bonanno1, 2, L. Rezzolla3, 4 and V. Urpin5, 6

1  INAF, Osservatorio Astrofisico di Catania, Catania, Italy
2  INFN, Sezione di Catania, Catania, Italy
3  SISSA, International School for Advanced Studies, Trieste, Italy
4  INFN, Sezione di Trieste, Trieste, Italy
5  AF Ioffe Institute of Physics and Technology, St. Petersburg, Russia
6  Isaac Newton Institute of Chile in Eastern Europe and Eurasia, St. Petersburg, Russia

(Received 16 July 2003 / Accepted 18 September 2003)

Abstract
We have investigated the turbulent mean-field dynamo action in protoneutron stars that are subject to convective and neutron finger instabilities. While the first one develops mostly in the inner regions of the star, the second one is favoured in the outer regions, where the Rossby number is much smaller and a mean-field dynamo action is more efficient. By solving the mean-field induction equation we have computed the critical spin period below which no dynamo action is possible and found it to be ~1 s for a wide range of stellar models. Because this critical period is substantially longer than the characteristic spin period of very young pulsars, we expect that a mean-field dynamo will be effective for most protoneutron stars.


Key words: MHD -- pulsars: general -- stars: neutron -- magnetic fields

Offprint request: V. Urpin, vadim.urpin@uv.es

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