A recently released X-ray view of Cassiopeia A, the remnant of an exploded star, shows several chemical elements manufactured during the explosion racing out into space. Silicon is in red, sulfur in yellow, calcium in green, and iron in purple. The expanding cloud contains enough of these four elements, which were forged inside the star, to make more than 100,000 planets as massive as Earth. Someday, the elements may be incorporated into new stars or planets. Cassiopeia A exploded around the year 1680 as seen from Earth, although there are no confirmed reports that anyone on Earth saw it, perhaps because it was wrapped in a cocoon of dust expelled from the star before its destruction. This image was obtained by Chandra X-Ray Observatory, a space telescope. [NASA/CXC/SAO]
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The brightest object beyond our own solar system wheels high overhead on winter nights. It’s in Cassiopeia the queen, whose brightest stars form a big letter M. It’s high in the north at nightfall.
Cassiopeia A outshines all the stars that make up the M. Don’t bother looking for it, though — it’s invisible to the eye alone. But it’s a different story at radio wavelengths — Cas A outshines everything except the Sun and a few other objects in the solar system. Yet Cassiopeia A is 11,000 light-years away, which provides an idea of its power.
Cas A is the remnant of a star that exploded as a supernova. The blast took place more than 300 years ago as seen from Earth, although there are no confirmed cases of anyone actually seeing it — a veil of gas and dust might have blocked its light.
The massive star quickly consumed the nuclear fuel in its core. The core collapsed, forming an ultra-dense neutron star. The layers of gas around the core then were blasted into space. Today those layers form a glowing cloud that’s expanding at millions of miles per hour.
The neutron star at the center of the cloud produces a powerful magnetic field. Electrons move through that field at high speeds. As they do so, they produce radio waves — making Cassiopeia A the brightest source of radio waves beyond the solar system.
Before the supernova explosion that blasted it to bits, Cas A might have produced a smaller outburst; more about that tomorrow.
Script by Damond Benningfield