In:
The Astrophysical Journal, American Astronomical Society, Vol. 933, No. 2 ( 2022-07-01), p. 136-
Kurzfassung:
We report high-precision X-ray monitoring observations in the 0.4–10 keV band of the luminous, long-period colliding wind binary Eta Carinae, up to and through its most recent X-ray minimum/periastron passage in 2020 February. Eta Carinae reached its observed maximum X-ray flux on 2020 January 7, at a flux level of 3.30 ×10 −10 ergs s −1 cm −2 , followed by a rapid plunge to its observed minimum flux, 0.03 × 10 −10 ergs s −1 cm −2 , near 2020 February 17. The NICER observations show an X-ray recovery from the minimum of only ∼16 days, the shortest X-ray minimum observed so far. We provide new constraints for the “deep” and “shallow” minimum intervals. Variations in the characteristic X-ray temperatures of the hottest observed X-ray emission indicate that the apex of the wind–wind “bow shock” enters the companion’s wind acceleration zone about 81 days before the start of the X-ray minimum. There is a steplike increase in column density just before the X-ray minimum, probably associated with the presence of dense clumps near the shock apex. During the recovery and after, the column density shows a smooth decline, which agrees with previous N H measurements made by Swift at the same orbital phase, indicating that the changes in the mass-loss rate are only a few percent over the two cycles. Finally, we use the variations in the X-ray flux of the outer ejecta seen by NICER to derive a kinetic X-ray luminosity of the ejecta of ∼10 41 ergs s −1 near the time of the “Great Eruption.”
Materialart:
Online-Ressource
ISSN:
0004-637X
,
1538-4357
DOI:
10.3847/1538-4357/ac69ce
Sprache:
Unbekannt
Verlag:
American Astronomical Society
Publikationsdatum:
2022
ZDB Id:
2207648-7
ZDB Id:
1473835-1
SSG:
16,12