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Astron. Astrophys. 349, L77-L80 (1999)

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Letter to the Editor

BeppoSAX observations of the atoll X-ray binary 4U 0614+091

S. Piraino 1,2,3, A. Santangelo 2, E.C. Ford 4 and P. Kaaret 1

1 Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
2 IFCAI/CNR, Via Ugo La Malfa 153, I-90146 Palermo, Italy
3 Dipartimento di Scienze Fisiche ed Astronomiche, via Archirafi 36, I-90123 Palermo, Italy
4 University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands

Received 2 July 1999 / Accepted 23 August 1999


We report the first simultaneous measurement of the broad band X-ray (0.3-150 keV) spectrum of the neutron star x-ray binary 4U 0614+091. Our data confirm the presence of a hard x-ray tail that can be modeled as thermal Comptonization of low-energy photons on electrons having a very high temperature, greater than 220 keV, or as a non-thermal powerlaw. We detected a spectral feature that can be interpreted as reprocessing, via Compton reflection, of the direct emission by an optically-thick disk and found a correlation between the photon index of the power-law tail and the fraction of radiation reflected which is similar to the correlation found for black hole candidate x-ray binaries and Seyfert galaxies.

Key words: accretion, accretion disks – stars: individual: 4U 0614+091 – stars: neutron – X-rays: stars

Send offprint requests to: Philip Kaaret (pkaaret@cfa.harvard.edu)

© European Southern Observatory (ESO) 1999

Online publication: September 13, 1999