Astron. Astrophys. 342, L57-L61 (1999)

Letter to the Editor

A transition from linear to circular polarization in pulsar radio emission

A. von Hoensbroech ^1,2 and H. Lesch <sup>2

1</sup> Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
² Institut für Astronomie und Astrophysik der Ludwig-Maximilian-Universität München, Scheinerstrasse 1, D-81679 München, Germany

Received 17 August 1998 / Accepted 13 January 1999

Abstract

At present three pulsars are known which clearly show a strongly increasing degree of circular polarization with frequency. As this is accompanied by a smooth decrease of linear polarization, we investigate, if this observation can be explained through a propagation mode transition from linear to circular polarization. Using a previously published model we find that the rate of change of the polarization types with frequency is well consistent with the theory.

The small number of only three objects does of course not allow to draw a general conclusion for the whole sample of pulsars. However we show that the very unusual behavior of these three objects can be well explained with this model and we discuss, why only so few such objects are presently known.

Key words: plasmas polarization stars: pulsars: general stars: pulsars: individual: PSR B0144+59 stars: pulsars: individual: PSR B1737-30 stars: pulsars: individual: PSR B1913+10

Send offprint requests to: A. von Hoensbroech (avh@mpifr-bonn.mpg.de)

© European Southern Observatory (ESO) 1999

Online publication: February 23, 1999

helpdesk@link.springer.de