The Expansion of the X-Ray Nebula Around η Car

Abstract The massive colliding wind binary system η Car is embedded in an X-ray emitting region having a characteristic temperature of few million degrees, associated with ejecta produced during the 1840s, and earlier outbursts. We use CHANDRA imaging observations obtained over past two decades to directly measure expansion nebula for first time. A combined CHANDRA/ACIS image shows faint, nearly uniform elliptic structure. This faint elliptical “shell” has similar orientation shape as Homunculus but about 3 times larger. proper motions brighter regions ring. compare spectra soft plasma XMM-Newton PN show that indicate decline flux which comparable derived from NICER observations. associate diffuse emission surrounding bright “ring” blast wave Great Eruption. suggest interaction this pre-existing clumps produces bright, broken extrapolate trend energy back time Eruption using simple model was kinetic Homunculus, suggesting equipartition between fast, low-density slower, dense ejecta.