Discovery of Outlying, High-Velocity Oxygen-Rich Ejecta in Cassiopeia A

Abstract

Hubble Space Telescope images of the young Galactic supernova remnant Cassiopeia A reveal a far larger population of outlying, high-velocity knots of ejecta with a broader range of chemical properties than previously suspected. We identify three main classes of outer ejecta: 1) Knots dominated by [N II] 6548,6583 emission; 2) Knots dominated by oxygen emission lines especially [O II] 7319,7330; and 3) Knots with emission line strengths similar to the [S II] strong FMK ejecta commonly seen in the main emission shell. The discovery of a significant population of O-rich ejecta situated in between the suspected N-rich outer photospheric layer and S-rich FMK-like ejecta suggests that the Cas A progenitor's chemical layers were not completely disrupted by the supernova explosion outside of the remnant's NE and SW high velocity `jet' regions. In addition, we find the majority of O-rich outer ejecta at projected locations out beyond (v = 6500 - 9000 km/s) the remnant's fastest moving Fe-rich X-ray emission material (6000 km/s) seen in Chandra and XMM data along the eastern limb. This suggests that penetration of Fe-rich material up through the S and Si-rich mantle did not extend past the progenitor's N or O-rich outer layers for at least this section of the remnant.

arXiv comment17 pages including 3 tables and 7 figures. To appear in ApJ

References in corpus (14)

• The Photometric Performance and Calibration of the HST Advanced Camera For Surveys
• Nucleosynthesis and Mixing in Cassiopeia A
• Non-spherical Core Collapse Supernovae I. Neutrino-Driven Convection, Rayleigh-Taylor Instabilities, and the Formation and Propagation of Metal Clumps
• A Million-Second Chandra View of Cassiopeia A
• Chandra Detection of the Forward and Reverse Shocks in Cassiopeia-A
• The Expansion Center and Dynamical Age of the Galactic Supernova Remnant Cassiopeia A
• Nucleosynthesis and Clump Formation in a Core Collapse Supernova
• On the Determination of Ejecta Structure and Explosion Asymmetry from the X-ray Knots of Cassiopeia A
• X-ray spectral imaging and Doppler mapping of Cassiopeia A
• Mapping the X-ray Emitting Ejecta in Cassiopeia A with Chandra
• Where was the Iron Synthesized in Cassiopeia A?
• The mass and energy budget of Cassiopeia A
• Hubble Space Telescope WFPC-2 Imaging of Cassiopeia A
• X- and Gamma-ray Studies of Cas A: Exposing Core Collapse to the Core

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