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| Paper: |
XMM-Newton Observations of the 2003 X-ray Minimum of η Carinae |
| Volume: |
367, Massive Stars in Interactive Binaries |
| Page: |
257 |
| Authors: |
Hamaguchi, K.; Corcoran, M.F.; Gull, T.; White, N.E.; Damineli, A.; Davidson, K. |
| Abstract: |
The XMM-Newton X-ray observatory took part in the multiwavelength observing campaign of the massive, evolved star η Carinae in 2003 during its recent X-ray minimum. This paper reports on the results of these observations, mainly from the aspect of spectral change. Hard X-ray emission from the point source of η Carinae was detected even during the minimum. During the minimum the observed flux above 3 keV was ~3×10−12 ergs cm−2 s−1, which is about one percent of the flux before the minimum. Changes in the spectral shape revealed two X-ray emission components in the central point source. One component is non-variable and has relatively cool plasma of kT ~1 keV and moderate absorption, NH ~5×1022 cm−2 . The plasma is probably located far from the star, possibly produced by the high-speed polar wind from η Carinae. The other high-temperature component has kT ~ 5 keV and is strongly variable. This component shows an increase in the apparent column density from 5×1022 cm−2 to 2×1023 cm−2 , probably originating near the heart of the binary system. These changes in NH were smaller than expected if the minimum is produced solely by an increase of hydrogen column density. The X-ray minimum seems to be dominated by a decrease of the apparent emission measure, suggesting that the brightest part of the X-ray emitting region is completely obscured during the minimum in the form of an eclipse. A “partial covering” model might explain the residual emission seen during the minimum. |
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