2025-11-19 カリフォルニア工科大学 (Caltech)
Webb’s mid-infrared image shows four coiled shells of dust around a pair of Wolf-Rayet stars known as Apep for the first time. Previous observations by other telescopes showed only one. Webb’s data also confirmed that there are three stars gravitationally bound to one another.Credit: Image: NASA, ESA, CSA, STScI; Science: Yinuo Han (Caltech), Ryan White (Macquarie University); Image Processing: Alyssa Pagan (STScI)
＜関連情報＞
- https://www.caltech.edu/about/news/rare-star-system-gives-insights-into-the-origins-of-carbon-dust-in-the-galaxy
- https://iopscience.iop.org/article/10.3847/1538-4357/ae12e5
JWSTが明らかにした衝突風連星アペプにおける塵の形成と進化 The Formation and Evolution of Dust in the Colliding-wind Binary Apep Revealed by JWST
Yinuo Han, Ryan M. T. White, Joseph R. Callingham, Ryan M. Lau, Benjamin J. S. Pope, Noel D. Richardson, and Peter G. Tuthill
The Astrophysical Journal Published: 2025 November 19
DOI:10.3847/1538-4357/ae12e5
Abstract
Carbon-rich Wolf–Rayet (W-R) stars are significant contributors of carbonaceous dust to the galactic environment; however, the mechanisms and conditions for formation and subsequent evolution of dust around these stars remain open questions. Here we present JWST observations of the W-R+W-R colliding-wind binary Apep, which reveal an intricate series of nested concentric dust shells that are abundant in detailed substructure. The striking regularity in these substructures between successive shells suggests an exactly repeating formation mechanism combined with a highly stable outflow that maintains a consistent morphology even after reaching 0.6 pc (assuming a distance of 2.4 kpc) into the interstellar medium. The concentric dust shells show subtle deviations from spherical outflow, which could reflect orbital modulation along the eccentric binary orbit or nonsphericity in the stellar wind. Tracking the evolution of dust across the multitiered structure, we measure the dust temperature evolution that can broadly be described assuming an amorphous carbon composition in radiative thermal equilibrium with the central stars. The temperature profile and orbital period place new distance constraints that support Apep being at a greater distance than previously estimated, reducing the line-of-sight and sky-plane wind speed discrepancy previously thought to characterize the system.
