Beppo SAX observations of CF Tucanae and TY Pyxidis

¹ INAF/Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
² INAF/Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy

Corresponding author: E. Franciosini, francio@astropa.unipa.it

Received: 24 September 2002
Accepted: 14 November 2002

Abstract

We present the results of BeppoSAX observations of the RS CVn binary systems CF Tuc and TY Pyx. A long-duration flare was detected on CF Tuc just at the beginning of the observation; a second smaller flare occurred about half a period later. The light curve of TY Pyx shows a significant orbital modulation of the quiescent emission with possible evidence for eclipses, and strong flares. We find that the coronae of the two stars are very similar: both systems have quiescent temperatures of ∼10 and 20–25 MK, with only a factor of two difference in the emission measures. During the flares, temperatures of ∼30–40 MK are reached; these temperatures are not high enough to give detectable hard X-ray emission in the PDS. Both stars have subsolar coronal metallicities: we confirm the very low coronal abundance of CF Tuc (), while for TY Pyx we find . For both stars the coronal metallicities are in good agreement with their measured photospheric abundances.