Cassiopeia A’s Reverse Shock and Its Effects on the Expanding SN Ejecta
Using optical and near-infrared images of the Cassiopeia A (Cas A) supernova remnant covering the time period 1951–2022, together with optical spectra of selected filaments, we present an investigation of Cas A’s reverse shock velocity and the effects it has on the remnant’s metal-rich ejecta. We fi...
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IOP Publishing
2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4365/adbf15 |
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| author | Robert A. Fesen Dan Milisavljevic Daniel Patnaude Roger A. Chevalier John C. Raymond McKinley Brumback Kathryn E. Weil |
| author_facet | Robert A. Fesen Dan Milisavljevic Daniel Patnaude Roger A. Chevalier John C. Raymond McKinley Brumback Kathryn E. Weil |
| author_sort | Robert A. Fesen |
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| description | Using optical and near-infrared images of the Cassiopeia A (Cas A) supernova remnant covering the time period 1951–2022, together with optical spectra of selected filaments, we present an investigation of Cas A’s reverse shock velocity and the effects it has on the remnant’s metal-rich ejecta. We find the sequence of optical ejecta brightening and the appearance of new optical ejecta indicating the advancement of the remnant’s reverse shock in the remnant’s main shell has velocities typically between 1000 and 2000 km s ^−1 , which is ∼1000 km s ^−1 less than recent measurements made in X-rays. We further find that the reverse shock appears to move much more slowly and is nearly even stationary in the sky frame along the remnant’s western limb. However, we do not find the reverse shock to move inward at velocities as large as ∼2000 km s ^−1 as has been reported. Optical ejecta in Cas A’s main emission shell have proper motions indicating outward tangential motions ≃3500–6000 km s ^−1 , with the smaller values preferentially along the remnant’s southern regions, which we speculate may be partially the cause of the remnant’s faint and more slowly evolving southern sections. Following interaction with the reverse shock, ejecta knots exhibit extended mass ablated trails $0\mathop{.}\limits^{^{\prime\prime} }2$ – $0\mathop{.}\limits^{^{\prime\prime} }5$ in length, leading to extended emission indicating reverse shock induced decelerated velocities as large as ≃1000 km s ^−1 . Such ablated material is most prominently seen in higher ionization line emissions, whereas denser parts of ejecta knots show surprisingly little deceleration. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
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| series | The Astrophysical Journal Supplement Series |
| spelling | doaj-art-431f39d38bb146688d97eb276d2ab86e2025-08-20T03:53:27ZengIOP PublishingThe Astrophysical Journal Supplement Series0067-00492025-01-0127811710.3847/1538-4365/adbf15Cassiopeia A’s Reverse Shock and Its Effects on the Expanding SN EjectaRobert A. Fesen0https://orcid.org/0000-0003-3829-2056Dan Milisavljevic1https://orcid.org/0000-0002-0763-3885Daniel Patnaude2https://orcid.org/0000-0002-7507-8115Roger A. Chevalier3John C. Raymond4https://orcid.org/0000-0002-7868-1622McKinley Brumback5https://orcid.org/0000-0002-4024-6967Kathryn E. Weil6https://orcid.org/0000-0002-8360-0831Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College , Hanover, NH 03755, USADepartment of Physics and Astronomy, Purdue University , 525 Northwestern Avenue, West Lafayette, IN 47907, USASmithsonian Astrophysical Observatory , MS-3, 60 Garden Street, Cambridge, MA 02138, USADepartment of Astronomy, University of Virginia , P.O. Box 400325, Charlottesville, VA 22904-4325, USACenter for Astrophysics , 60 Garden Street, Cambridge, MA 02176, USADepartment of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College , Hanover, NH 03755, USA; Department of Physics, Middlebury College , Middlebury, VT 05753, USADepartment of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College , Hanover, NH 03755, USA; Department of Physics and Astronomy, Purdue University , 525 Northwestern Avenue, West Lafayette, IN 47907, USAUsing optical and near-infrared images of the Cassiopeia A (Cas A) supernova remnant covering the time period 1951–2022, together with optical spectra of selected filaments, we present an investigation of Cas A’s reverse shock velocity and the effects it has on the remnant’s metal-rich ejecta. We find the sequence of optical ejecta brightening and the appearance of new optical ejecta indicating the advancement of the remnant’s reverse shock in the remnant’s main shell has velocities typically between 1000 and 2000 km s ^−1 , which is ∼1000 km s ^−1 less than recent measurements made in X-rays. We further find that the reverse shock appears to move much more slowly and is nearly even stationary in the sky frame along the remnant’s western limb. However, we do not find the reverse shock to move inward at velocities as large as ∼2000 km s ^−1 as has been reported. Optical ejecta in Cas A’s main emission shell have proper motions indicating outward tangential motions ≃3500–6000 km s ^−1 , with the smaller values preferentially along the remnant’s southern regions, which we speculate may be partially the cause of the remnant’s faint and more slowly evolving southern sections. Following interaction with the reverse shock, ejecta knots exhibit extended mass ablated trails $0\mathop{.}\limits^{^{\prime\prime} }2$ – $0\mathop{.}\limits^{^{\prime\prime} }5$ in length, leading to extended emission indicating reverse shock induced decelerated velocities as large as ≃1000 km s ^−1 . Such ablated material is most prominently seen in higher ionization line emissions, whereas denser parts of ejecta knots show surprisingly little deceleration.https://doi.org/10.3847/1538-4365/adbf15Supernova remnantsCore-collapse supernovaeInterstellar emissionsFilamentary nebulae |
| spellingShingle | Robert A. Fesen Dan Milisavljevic Daniel Patnaude Roger A. Chevalier John C. Raymond McKinley Brumback Kathryn E. Weil Cassiopeia A’s Reverse Shock and Its Effects on the Expanding SN Ejecta The Astrophysical Journal Supplement Series Supernova remnants Core-collapse supernovae Interstellar emissions Filamentary nebulae |
| title | Cassiopeia A’s Reverse Shock and Its Effects on the Expanding SN Ejecta |
| title_full | Cassiopeia A’s Reverse Shock and Its Effects on the Expanding SN Ejecta |
| title_fullStr | Cassiopeia A’s Reverse Shock and Its Effects on the Expanding SN Ejecta |
| title_full_unstemmed | Cassiopeia A’s Reverse Shock and Its Effects on the Expanding SN Ejecta |
| title_short | Cassiopeia A’s Reverse Shock and Its Effects on the Expanding SN Ejecta |
| title_sort | cassiopeia a s reverse shock and its effects on the expanding sn ejecta |
| topic | Supernova remnants Core-collapse supernovae Interstellar emissions Filamentary nebulae |
| url | https://doi.org/10.3847/1538-4365/adbf15 |
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