Near-Infrared Spectroscopy of Dense Ejecta Knots in the Outer Eastern Area of the Cassiopeia A Supernova Remnant

Abstract

The Cassiopeia A supernova remnant has a complex structure, manifesting the multidimensional nature of core-collapse supernova explosions. To further understand this, we carried out near-infrared multi-object spectroscopy on the ejecta knots located in the "northeastern (NE) jet" and the "Fe K plume" regions, which are two distinct features in the outer eastern area of the remnant. Our study reveals that the knots exhibit varying ratios of [S II] 1.03 $\mu$m, [P II] 1.189 $\mu$m, and [Fe II] 1.257 $\mu$m lines depending on their locations within the remnant, suggesting regional differences in elemental composition. Notably, the knots in the NE jet are mostly 'S-rich' with weak or no [P II] lines, implying that they originated below the explosive Ne burning layer, consistent with the results of previous studies. We detected no ejecta knots exhibiting only [Fe II] lines in the NE jet area that are expected in the jet-driven SN explosion model. Instead, we discovered a dozen 'Fe-rich' knots in the Fe K plume area. We propose that they are dense knots produced by a complete Si burning with $\alpha$-rich freezeout in the innermost region of the progenitor and ejected with the diffuse X-ray emitting Fe ejecta but decoupled after crossing the reverse shock. In addition to these metal-rich ejecta knots, several knots emitting only He I 1.083 $\mu$m lines were detected, and their origin remains unclear. We also detected three extended H emission features of circumstellar or interstellar origin in this area and discuss its association with the supernova remnant.

arXiv comment30 pages, 16 figures, submitted to ApJ

References in corpus (64)

• The chemical composition of the Sun
• Mass Loss: Its Effect on the Evolution and Fate of High-Mass Stars
• Nucleosynthesis in Massive Stars With Improved Nuclear and Stellar Physics
• On the Nature of Core Collapse Supernova Explosions
• Scattering by Interstellar Dust Grains: Optical and Ultraviolet
• Simulations of Magnetically-Driven Supernova and Hypernova Explosions in the Context of Rapid Rotation
• The Magnetorotational Instability in Core Collapse Supernova Explosions
• Jet-Induced Explosions of Core Collapse Supernovae
• The Cassiopeia A Supernova was of Type IIB
• The Expansion Asymmetry and Age of the Cassiopeia A Supernova Remnant
• 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
• Three-Dimensional Simulations of Mixing Instabilities in Supernova Explosions
• Chandra Detection of the Forward and Reverse Shocks in Cassiopeia-A
• A Chandra X-ray Survey of Ejecta in the Cassiopeia A Supernova Remnant
• The Expansion Center and Dynamical Age of the Galactic Supernova Remnant Cassiopeia A
• Nucleosynthesis and Clump Formation in a Core Collapse Supernova
• Constraints on the Progenitor of Cassiopeia A
• Asymmetric Supernovae from Magneto-Centrifugal Jets
• The Three-Dimensional Structure of Cassiopeia A
• X-ray spectral imaging and Doppler mapping of Cassiopeia A
• Production and Distribution of ${}^{44}$Ti and ${}^{56}$Ni in a Three-dimensional Supernova Model Resembling Cassiopeia A
• The dust mass in Cassiopeia A from a spatially resolved Herschel analysis
• Instabilities and Clumping in Type Ia Supernova Remnants
• The distribution of radioactive ${}^{44}$Ti in Cassiopeia A
• Cassiopeia A and its Clumpy Presupernova Wind
• A Detailed Kinematic Map of Cassiopeia A's Optical Main Shell and Outer High-Velocity Ejecta
• Modeling SNR Cassiopeia A from the Supernova Explosion to its Current Age: The role of post-explosion anisotropies of ejecta
• Supernova Fallback as Origin of Neutron Star Spins and Spin-kick Alignment
• The fully developed remnant of a neutrino-driven supernova: Evolution of ejecta structure and asymmetries in SNR Cassiopeia A
• Phosphorus in the Young Supernova Remnant Cassiopeia A
• The First Measurement of Cassiopeia A's Forward Shock Expansion Rate
• The Dynamics, Destruction, and Survival of Supernova-Formed Dust Grains
• MMT & Magellan Infrared Spectrograph
• The Three-Dimensional Structure of Interior Ejecta in Cassiopeia A at High Spectral Resolution
• Dynamics of Fe-Ni Bubbles in Young Supernova Remnants
• The infancy of core-collapse supernova remnants
• The Polar Regions of Cassiopeia A: The Aftermath of a Gamma Ray Burst?
• An HST Survey of the Highest-Velocity Ejecta in Cassiopeia A
• Ejecta Knot Flickering, Mass Ablation, and Fragmentation in Cassiopeia A
• The Reddening Towards Cassiopeia A's Supernova: Constraining the 56Ni Yield
• Infrared [Fe II] Emission Lines from Radiative Atomic Shocks
• X- and Gamma-ray Studies of Cas A: Exposing Core Collapse to the Core
• Near-Infrared Spectroscopy of the Cassiopeia A and Kepler Supernova Remnants
• The Kinematic and Plasma Properties of X-ray Knots in Cassiopeia A from the Chandra HETGS
• The role of jets in exploding supernovae and in shaping their remnants
• Data Reduction Pipeline for the MMT and Magellan Infrared Spectrograph
• High-entropy ejecta plumes in Cassiopeia A from neutrino-driven convection
• Molecular gas toward supernova remnant Cassiopeia A
• Empirical determination of Einstein A-coefficient ratios of bright [Fe II] lines
• Near-Infrared Knots and Dense Fe Ejecta in the Cassiopeia A Supernova Remnant
• A Deep Near-Infrared [Fe II]+[Si I] Emission Line Image of the Supernova Remnant Cassiopeia A
• The Temperature and Ionization of Unshocked Ejecta in Cas A
• Type Ia Supernova Remnants: Shaping by Iron Bullets
• Three-dimensional morphological asymmetries in the ejecta of Cassiopeia A using a component separation method in X-rays
• Detection of the Red Supergiant Wind from the Progenitor of Cassiopeia A
• Near-infrared Extinction due to Cool Supernova Dust in Cassiopeia A
• Detection of Pristine Circumstellar Material of the Cassiopeia A Supernova
• A Decade-Baseline Study of the Plasma States of Ejecta Knots in Cassiopeia A
• Near-Infrared Spectroscopy of Young Galactic Supernova Remnants
• Discovery of Stable Titanium at the Northeastern Jet of Cassiopeia A: Need for a Weak Jet Mechanism?
• He abundance of Dense Circumstellar Clumps in the Cassiopeia A Supernova Remnant
• X-ray Studies of the Inverted Ejecta Layers in the Southeast Area of Cassiopeia A

Cited by in corpus (1)

• A First-look at Spatially-resolved Infrared Supernova Remnants in M33 with JWST