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Astron. Astrophys. 330, 1060-1066 (1998)

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Strong radio flaring period in UX Arietis

C. Trigilio, P. Leto and G. Umana

Istituto di Radioastronomia del C.N.R., Stazione VLBI di Noto, C.P. 141, Noto, Italy

Received 20 June 1995 / Accepted 24 October 1997


In January 1993 we observed the RS CVn-type binary system UX Ari at 6 cm using the 32 m radiotelescope of Noto, with a temporal coverage of about 12 hours per day. The source was found to be in a very active period, with a continuous series of radio flares of flux densities up to 350 mJy. The analysis of the data shows that the radio emission consists of two different components: a continuous series of strong radio flares and an orbital phase dependent component, with a minimum of emission around phase [FORMULA].

The amplitude of the radio flares and their time of occurrence do not depend on the orbital phase, suggesting that the region where they originate is always visible from Earth.

A bright and stable active region, localized in the hemisphere of the K star not visible from the G star, seems to account for the orbital phase dependence of the radio emission.

Key words: binaries: close – stars: coronae – stars: flare – stars: individual: UX Ari – radio continuum: stars

Send offprint requests to: C. Trigilio, trigilio@ira.noto.cnr.it

© European Southern Observatory (ESO) 1998

Online publication: January 27, 1998