2010ApJ...725.1528C -
Astrophys. J., 725, 1528-1535 (2010/December-3)
Recent X-ray variability of η Carinae: the quick road to recovery.
CORCORAN M.F., HAMAGUCHI K., PITTARD J.M., RUSSELL C.M.P., OWOCKI S.P., PARKIN E.R. and OKAZAKI A.
Abstract (from CDS):
We report continued monitoring of the superluminous binary system η Car by the Proportional Counter Array on the Rossi X-ray Timing Observatory (RXTE) through the 2009 X-ray minimum. The RXTE campaign shows that the minimum began on 2009 January 16, consistent with the phasings of the two previous minima, and overall, the temporal behavior of the X-ray emission was similar to that observed by RXTE in the previous two cycles. However, important differences did occur. The 2-10 keV X-ray flux and X-ray hardness decreased in the 2.5 year interval leading up to the 2009 minimum compared to the previous cycle. Most intriguingly, the 2009 X-ray minimum was about 1 month shorter than either of the previous two minima. During the egress from the 2009 minimum the X-ray hardness increased markedly as it had during egress from the previous two minima, although the maximum X-ray hardness achieved was less than the maximum observed after the two previous recoveries. We suggest that the cycle-to-cycle variations, especially the unexpectedly early recovery from the 2009 X-ray minimum, might have been the result of a decline in η Car's wind momentum flux produced by a drop in η Car's mass loss rate or wind terminal velocity (or some combination), though if so the change in wind momentum flux required to match the X-ray variation is surprisingly large.
Abstract Copyright:
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Journal keyword(s):
binaries: general - stars: early-type - stars: individual: Eta Carinae - X-rays: stars
Simbad objects:
2
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