The Green Monster Hiding in Front of Cas A: JWST Reveals a Dense and Dusty Circumstellar Structure Pockmarked by Ejecta Interactions
Year: 2024
Type: article
Abstract: JWST observations of the young Galactic supernova remnant Cassiopeia A revealed an unexpected structure seen as a green emission feature in colored composite MIRI F1130W and F1280W images?hence dubbed the Green Monster?that stretches across the central parts of the remnant in projection. Combining the kinematic information from NIRSpec and the MIRI Medium Resolution Spectrograph with the multiwavelength imaging from NIRCam and MIRI, we associate the Green Monster with circumstellar material (CSM) that was lost during an asymmetric mass-loss phase. MIRI images are dominated by dust emission, but their spectra show emission lines from Ne, H, and Fe with low radial velocities indicative of a CSM nature. An X-ray analysis of this feature in a companion paper supports its CSM nature and detects significant blueshifting, thereby placing the Green Monster on the nearside, in front of the Cas A supernova remnant. The most striking features of the Green Monster are dozens of almost perfectly circular 1??3? sized holes, most likely created by interaction between high-velocity supernova ejecta material and the CSM. Further investigation is needed to understand whether these holes were formed by small 8000?10,500 km s?1 N-rich ejecta knots that penetrated and advanced out ahead of the remnant?s 5000?6000 km s?1 outer blast wave or by narrow ejecta fingers that protrude into the forward-shocked CSM. The detection of the Green Monster provides further evidence of the highly asymmetric mass loss that Cas A?s progenitor star underwent prior to its explosion.
DOI: 10.13016/m22pbj-muz3
Authors: De Looze, Ilse, Milisavljevic, Dan, Temim, Tea, Dickinson, Danielle, Fesen, Robert, Arendt, Richard, Chastenet, Jeremy, Orlando, Salvatore, Vink, Jacco, Barlow, Michael J., Kirchschlager, Florian, Priestley, Felix D., Raymond, John C., Rho, Jeonghee, Sartorio, Nina S., Scheffler, Tassilo, Schmidt, Franziska, Blair, William P., Fox, Ori, Fryer, Christopher, Janka, Hans-Thomas, Koo, Bon-Chul, Laming, J. Martin, Matsuura, Mikako, Patnaude, Dan, Rela�O, M�Nica, Rest, Armin, Schmidt, Judy, Smith, Nathan, Sravan, Niharika
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, National Aeronautics and Space Administration, Space Telescope Science Institute, European Commission, Deutsche Forschungsgemeinschaft, Belgian Federal Science Policy Office, Fonds Wetenschappelijk Onderzoek, Nuclear Safety and Security Commission, Vlaamse regering, Goddard Space Flight Center, Science and Technology Facilities Council, Office of Naval Research, H2020 European Research Council
Awards: G103270039, A Programme of Technology, Astrophysics and Cosmology in Cardiff, 2022-2025, Dusty Beginnings, G1824938559, G1897041155, G201248631, Collaborative Research: Constraining Supernova Progenitor Systems and Explosion Mechanisms Through 3D Reconstruction of Supernova Remnants, G256731684, The origin of cosmic dust in galaxies, G3657338460, G4066435496, G4090823411, G434337789, EXC 2094: ORIGINS: Vom Ursprung des Universums bis zu den ersten Bausteinen des Lebens, G4599274524, SFB 1258: Neutrinos und Dunkle Materie in der Astro und Teilchenphysik (NDM), G6866600364, WoU-MMA: Collaborative Research: Advancing the SuperNova Early Warning System, G844997840, Collaborative Research: Constraining Supernova Progenitor Systems and Explosion Mechanisms Through 3D Reconstruction of Supernova Remnants
OpenAlex ID: W6922064785
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