An HST Survey of the Highest-Velocity Ejecta in Cassiopeia A

Abstract

We present Hubble Space Telescope WFC3/IR images of the Cassiopeia A supernova remnant that survey its high-velocity, S-rich debris in the NE jet and SW counterjet regions through [S III] 9069, 9531 and [S II] 10,287 - 10,370 line emissions. We identify nearly 3400 sulfur emitting knots concentrated in ~120 degree wide opposing streams, almost triple the number previously known. The vast majority of these ejecta knots lie at projected distances well out ahead of the remnant's forward blast wave and main shell ejecta, extending to angular distance of 320" to the NE and 260" to the SW from the center of expansion. Such angular distances imply undecelerated ejecta knot transverse velocities of 15,600 and 12,700 km/s respectively, assuming an explosion date ~1670 AD and a distance of 3.4 kpc. Optical spectra of knots near the outermost tip of the NE ejecta stream show strong emission lines of S, Ca, and Ar. We estimate a total mass ~0.1 Msun and a kinetic energy of at least ~1 x10^50 erg for S-rich ejecta in the NE jet and SW counterjet. Although their broadness and kinetic energy argue against the Cas~A SN being a jet-induced explosion, the jets are kinematically and chemically distinct from the rest of the remnant. This may reflect an origin in a jet-like mechanism that accelerated interior material from a Si,S,Ar,Ca-rich region near the progenitor's core up through the mantle and H,He,N and O-rich outer layers with velocities that greatly exceeded that of the rapidly expanding photosphere.

24 pages, 18 figures: accepted to the Astrophysical Journal

References in corpus (13)

• The Supernova -- Gamma-Ray Burst Connection
• The Cassiopeia A Supernova was of Type IIB
• The Expansion Asymmetry and Age of the Cassiopeia A Supernova Remnant
• Asymmetries in core-collapse supernovae from maps of radioactive ${}^{44}$Ti in CassiopeiaA
• The metamorphosis of Supernova SN2008D/XRF080109: a link between Supernovae and GRBs/Hypernovae
• Scattered-Light Echoes from the Historical Galactic Supernovae Cassiopeia A and Tycho (SN 1572)
• The Bubble-like Interior of the Core-Collapse Supernova Remnant Cassiopeia A
• The Broad-Lined Type Ic SN 2012ap and the Nature of Relativistic Supernovae Lacking a Gamma-ray Burst Detection
• The Polar Regions of Cassiopeia A: The Aftermath of a Gamma Ray Burst?
• Jets as diagnostics of the circumstellar medium and the explosion energetics of supernovae: the case of Cas A
• The Shape of Cas A
• Spatially Resolved X-ray Spectroscopy of Vela Shrapnel A
• Interaction between Cassiopeia A and Nearby Molecular Clouds

Cited by in corpus (37)

• The Observer's Guide to the Gamma-Ray Burst-Supernova Connection
• Production and Distribution of ${}^{44}$Ti and ${}^{56}$Ni in a Three-dimensional Supernova Model Resembling Cassiopeia A
• The jet feedback mechanism (jfm) in stars, galaxies and clusters
• 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
• Turbulence in Core-Collapse Supernovae
• Variability of the Lowest Mass Objects in the AB Doradus Moving Group
• Core collapse supernova remnants with ears
• A JWST Survey of the Supernova Remnant Cassiopeia A
• Exploring the Properties of Choked Gamma-Ray Bursts with IceCube's High Energy Neutrinos
• On the type Ia supernovae 2007on and 2011iv: Evidence for Chandrasekhar-mass explosions at the faint end of the luminosity-width relationship
• High-entropy ejecta plumes in Cassiopeia A from neutrino-driven convection
• Luminous type IIP SN 2013ej with high-velocity Ni-56 ejecta
• Three-Dimensional Kinematic Reconstruction of the Optically-Emitting, High-Velocity, Oxygen-Rich Ejecta of Supernova Remnant N132D
• What planetary nebulae can tell us about jets in core collapse supernovae
• The Continuing Story of SN IIb 2013df: New Optical and IR Observations and Analysis
• Numerically Modeling the First Peak of the Type IIb SN 2016gkg
• The Supernova -- Supernova Remnant Connection
• The Morphologies and Kinematics of Supernova Remnants
• The two promising scenarios to explode core collapse supernovae
• 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
• Key Issues Review: Numerical studies of turbulence in stars
• Asymmetries of Heavy Elements in the Young Supernova Remnant Cassiopeia A
• Discovery of Stable Titanium at the Northeastern Jet of Cassiopeia A: Need for a Weak Jet Mechanism?
• Identifying jittering-jet-shaped ejecta in the Cygnus Loop supernova remnant
• The two most recent thermonuclear supernovae in the Local Group: radio constraints on their progenitors and evolution
• X-ray Studies of the Inverted Ejecta Layers in the Southeast Area of Cassiopeia A
• Storing magnetic fields in pre-collapse cores of massive stars
• HST Proper Motion Measurements of Supernova Remnant N132D: Center of Expansion and Age
• Implications of post-kick jets in core collapse supernovae
• Near-Infrared Spectroscopy of Dense Ejecta Knots in the Outer Eastern Area of the Cassiopeia A Supernova Remnant
• XRISM Observations of Cassiopeia A: Overview, Atomic Data, and Spectral Models
• The rotational shear in pre-collapse cores of massive stars
• Decadal brightening in the northeastern non-thermal filament of Cassiopeia A
• The forward and reverse shock dynamics of Cassiopeia A
• Mantle Degassing Lifetimes through Galactic Time and the Maximum Age Stagnant-lid Rocky Exoplanets can Support Temperate Climates