Images by Date
Images by Category
Solar System
Stars
Exoplanets
White Dwarfs
Supernovas
Neutron Stars
Black Holes
Milky Way Galaxy
Normal Galaxies
Quasars
Galaxy Clusters
Cosmology/Deep Field
Miscellaneous
Images by Interest
Space Scoop for Kids
4K JPG
Multiwavelength
Sky Map
Constellations
Photo Blog
Top Rated Images
Image Handouts
Desktops
Fits Files
Visual descriptions
Image Tutorials
Photo Album Tutorial
False Color
Cosmic Distance
Look-Back Time
Scale & Distance
Angular Measurement
Images & Processing
AVM/Metadata
Image Use Policy
Web Shortcuts
Chandra Blog
RSS Feed
Chronicle
Email Newsletter
News & Noteworthy
Image Use Policy
Questions & Answers
Glossary of Terms
Download Guide
Get Adobe Reader
More Information
Supernovas & Supernova Remnants
Related Podcasts
Tour: NASA's Chandra Peers Into Densest and Weirdest Stars
Download Image

More Information

More Images
Chandra 3-color X-ray Image of Cassiopeia A
(Credit: NASA/CXC/SAO/P.Slane et al.)

Animation & Video

More Releases
Cassiopeia A
Cassiopeia A
(26 Aug 24)
Cassiopeia A
Cassiopeia A
(22 Jul 24)
Cassiopeia A
Cassiopeia A
(24 Apr 24)
Cassiopeia A
Cassiopeia A
(08 Jan 24)
Cassiopeia A
Cassiopeia A
(18 Oct 22)
Cassiopeia A
Cassiopeia A
(02 Feb 22)
Cassiopeia A
Cassiopeia A
(21 Apr 21)
Cassiopeia A
Cassiopeia A
(26 Aug 19)
Cassiopeia A
Cassiopeia A
(12 Dec 17)
Cassiopeia A
Cassiopeia A
(15 Nov 13)
Cassiopeia A
Cassiopeia A
(29 Mar 12)
Cassiopeia A
Cassiopeia A
(23 Feb 11)
Cassiopeia A
Cassiopeia A
(04 Nov 09)
Cassiopeia A
Cassiopeia A
(06 Jan 09)
Cassiopeia A
Cassiopeia A
(06 Jan 09)
Cassiopeia A
Cassiopeia A
(15 Nov 06)
Cassiopeia A
Cassiopeia A
(13 Jun 05)
Cassiopeia A
Cassiopeia A
(19 Aug 02)
Cassiopeia A
Cassiopeia A
(27 Jun 00)
Cassiopeia A
Cassiopeia A
(21 Dec 99)
Cassiopeia A
Cassiopeia A
(26 Aug 99)

Related Images
Vela Pulsar Jet
Vela Pulsar Jet
(30 Jun 03)
Crab Nebula
Crab Nebula
(19 Sep 02)
Cassiopeia A:
Deepest Image of Exploded Star Uncovers Bipolar Jets


Cassiopeia A
Credit: NASA/CXC/GSFC/U.Hwang et al.

This spectacular image of the supernova remnant Cassiopeia A is the most detailed image ever made of the remains of an exploded star. The one-million-second image shows a bright outer ring (green) ten light years in diameter that marks the location of a shock wave generated by the supernova explosion. A large jet-like structure that protrudes beyond the shock wave can be seen in the upper left. In the accompanying image, specially processed to highlight silicon ions, a counter-jet can be seen on the lower right.

Surprisingly, the X-ray spectra show that the jet and counter-jet are rich in silicon atoms and relatively poor in iron atoms. This indicates that the jets formed soon after the initial explosion of the star; otherwise, the jets should have contained large quantities of iron from the star's central regions

The bright blue fingers located near the shock wave on the lower left are composed almost purely of iron gas. This iron was produced in the central, hottest regions of the star and somehow ejected in a direction almost perpendicular to the jets.

The bright source at the center of the image is presumed to be a neutron star created during the supernova. Unlike the rapidly rotating neutron stars in the Crab Nebula and Vela supernova remnants that are surrounded by dynamic magnetized clouds of electrons called pulsar wind nebulas, this neutron star is quiet, faint, and so far shows no evidence for pulsed radiation.

A working hypothesis is that the explosion that created Cassiopeia A produced high-speed jets similar to but less energetic than the hypernova jets thought to produce gamma-ray bursts. During the explosion, the neutron star may have developed an extremely strong magnetic field that helped to accelerate the jets. This strong magnetic field later stifled any pulsar wind activity, so the neutron star today resembles other strong-field neutron stars (a.k.a. "magnetars") in lacking a pulsar wind nebula.

Fast Facts for Cassiopeia A:
Credit  NASA/CXC/GSFC/U.Hwang et al.
Scale  Image is 8 arcmin across.
Category  Supernovas & Supernova Remnants
Coordinates (J2000)  RA 23h 23m 26.7s | Dec +58° 49' 03.00"
Constellation  Cassiopeia
Observation Dates  Nine observations in 2004: Feb 8, Apr 14, 18, 20, 22, 25 28, May 01, 05
Observation Time  278 hours
Obs. IDs  4634-4639, 5196, 5319-5320
Color Code  Left panel: Energy (Red=1.78-2.0 keV; Green=4.2-6.4 keV; Blue=6.52-6.95 keV); Right panel: Intensity
Instrument  ACIS
Also Known As Cas A
References U. Hwang et al. 2004, The Astrophys. J. Letters, (in press)
Distance Estimate  11,000 light years
Release Date  August 23, 2004