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Title: VLA multifrequency observations of RSCVn binaries
Author: García-Sánchez, J.
Paredes i Poy, Josep Maria
Ribó Gomis, Marc
Keywords: Estels
Estels binaris
Polarització (Llum)
Double stars
Radio astronomy
Polarization (Light)
Issue Date: 2003
Publisher: Springer Verlag
Abstract: We present multiepoch Very Large Array (VLA) observations at 1.4 GHz, 4.9 GHz, 8.5 GHz and 14.9 GHz for a sample of eight RS CVn binary systems. Circular polarization measurements of these systems are also reported. Most of the fluxes observed are consistent with incoherent emission from mildly relativistic electrons. Several systems show an increase of the degree of circular polarization with increasing frequency in the optically thin regime, in conflict with predictions by gyrosynchrotron models. We observed a reversal in the sense of circular polarization with increasing frequency in three non-eclipsing systems: EI Eri, DM Uma and HD 8358. We find clear evidence for coherent plasma emission at 1.4 GHz in the quiescent spectrum of HD 8358 during the helicity reversal. The degrees of polarization of the other two systems could also be accounted for by a coherent emission process. The observations of ER Vul revealed two U-shaped flux spectra at the highest frequencies. The U-shape of the spectra may be accounted for by an optically thin gyrosynchrotron source for the low frequency part whereas the high frequency part is dominated by a thermal emission component.
Note: Versió postprint del document publicat a:
It is part of: Astronomy and Astrophysics, 2003, vol. 403, p. 613-624
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ISSN: 0004-6361
Appears in Collections:Articles publicats en revistes (Física Quàntica i Astrofísica)

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