High energy phenomena in eta carinae |
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| Authors: | Roberto F Viotti Lucio Angelo Antonelli Sonja Rebecchi Corinne Rossi |
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| Institution: | (1) Istituto di Astrofisica Spaziale, CNR, 00133 Roma, Italy;(2) Osservatorio Astronomico di Roma, 00040 Monte Porzio, Italy;(3) ASI Science Data Centre, ESA-ESRIN, 00044 Frascati, Italy;(4) Dipartimento di Fisica, Università La Sapienza, 00185 Roma, Italy |
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| Abstract: | We have investigated with BeppoSAX the long term behaviour of the harder X-ray component of the supposed supermassive binary
system η Car along its 5.52 year cycle. We have found that in March 1998 during egress from the last December 1997 eclipse,
this component was the same as outside eclipse, but for a large (×3.5) increase of NH
h
, that can be attributed to the presence or formation of opaque matter in front of the source near periastron. Unexpectedly,
at that time the iron 6.7 keV emission line was 40% stronger. BeppoSAX has for the first time found ahard X-ray tail extending to at least 50 keV, that cannot be adequately fitted with an additional hotter thermal component. The 2–100 keV
spectrum of η Car is instead well fitted with an absorbed powerlaw spectrum with photon index 2.53, suggesting non-thermal
emission as an alternative model for the core source. |
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| Keywords: | Colliding winds model non-thermal emission stars: η Car X-ray emission |
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