Cassiopeia A


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Cassiopeia A

An intense radio source 2.8 kiloparsecs distant in the constellation Cassiopeia. It has the largest flux density at low frequencies of all the discrete radio sources (apart from the Sun), the value being about 8200 jansky at 178 megahertz, and a spectral index of –0.77. The flux drops by about 1% per year. It is a supernova remnant – probably of a supernova explosion (unrecorded) of a massive (˜50 MO) star in the late 17th century – and has a ringlike structure about four arc minutes in diameter. The radio radiation is by synchrotron emission and the radio shell is expanding at 2300 km s–1. It is also an extended source of soft X-rays.

Cassiopeia A

[‚kas·ē·ə′pē·ə ′ā]
(astronomy)
One of the strongest discrete radio sources, located in the constellation Cassiopeia, associated with patches of filamentary nebulosity which are probably remnants of a supernova.
References in periodicals archive ?
The supernova remnant has been identified by NASA as Cassiopeia A, also known as Cas A.
MARYLAND (CyHAN)- One of the most famous objects in the sky - the Cassiopeia A supernova remnant - is now on display like never before.
Two independent research teams studied the supernova remnant Cassiopeia A, or Cas A for short, the remains of a massive star 11,000 light-years away that would have appeared to explode about 330 years ago as observed from Earth.
In infrared portraits taken a year apart, NASA's Spitzer Space Telescope examined Cassiopeia A, the youngest known super-nova remnant in the galaxy.
The new image shows red, white, blue, pink and green gas streamers flowing from Cassiopeia A, part of the constellation Cassiopeia - named for an Ethiopian queen.
Cassiopeia A is the remains of a star that exploded about 11,000 years ago.
Trained on Cassiopeia A for viewing sessions totaling 11.5 days, NASA's Chandra X-ray Observatory has now taken the most detailed portrait ever recorded of any supernova remnant.
Astronomers had expected that the star would have left behind a superdense, burned-out cinder at the core of the remnant, dubbed Cassiopeia A. Previous X-ray missions, as well as observations with radio and visible-light telescopes on the ground, revealed no such object, however.
Cassiopeia A is a beautiful cascade of gases surrounding a neutron star born in a supernova some 300 years ago.
In contrast, Cassiopeia A, the youngest known supernova remnant in the Milky Way, appears messier.
And the youngest known remnant in the Milky Way, Cassiopeia A, tells a tale about a star that seems to have turned itself inside out.