Supernova Remnants
Supernova Remnants
| Group Name | snr |
| Reference | Galactic Supernova Remnants Catalogue (Ilovaisky+ 1972) |
| Prepared by | Brian Abbott (AMNH/Hayden) |
| Labels | Yes |
| Files | sn_remnant.speck, sn_remnant.label |
| Dependencies | none |
| Census | 116 supernova remnants and 83 labels |
A supernova remnant is the nebulous gas left over from a supernova explosion. During a supernova, one-fifth the mass of the original star can be expelled. This gas expands at great speeds, 10,000 to 20,000 km/sec, and rams into the surrounding interstellar gas. The expanding gas excites the surrounding gas, causing it to glow and producing the nebulous cloud we observe from Earth.
A supernova remnant contains a neutron star or pulsar at its center, the core of the dying star. The cloud that enshrouds the core does not last long, though. After about 50,000 years, the gas mixes into the interstellar medium and no longer glows. Astronomically, this is a very short time, so the supernova remnants we see must be left from explosions that have occurred very recently.
The most recent supernova occurred in the Large Magellanic Cloud in 1987. The most studied supernova in history, SN 1987A is the latest in a series of explosions observed by astronomers. In 1054, the Chinese recorded the appearance of a “guest star” in Taurus. Bright enough to see in the daytime, the star brightened rapidly, then faded from sight over the next two years. Modern astronomers pointed their telescopes to the star and found a gas cloud about 4.4 light-years in radius expanding at a rate of 1,400 km/sec. Projecting this expansion back in time, they found that the explosion began about 900 years ago, confirming the Chinese records. We call the object Messier 1, or the Crab Nebula.
In the past 2,000 years, only 14 supernovae (SN) have been recorded in our own Galaxy. Aside from SN 1054, Arab astronomers observed one in 1006 and European astronomers observed SN 1572 (Tycho's supernova Cassiopeia A) and SN 1604 (Kepler's supernova in Serpens). For the next 383 years, no supernovae were seen, until February 23, 1987, when a “new star,” SN 1987 A, appeared in the Large Magellanic Cloud.
Location in the Galaxy
Similar to pulsars, supernova remnants are found in the disk of the Galaxy. These remnants are short-lived nebulae and will be visible only in areas of active star formation. Because they have such short lifetimes, you would expect them to be tightly correlated with the Galactic disk and, relative to the pulsars, lie very close to the plane of the Galaxy.
Labels
The labels are a hodgepodge of different catalog source names. A few are in “English,” such as the Cyg Loop for the Cygnus Loop (the Veil Nebula region). Some have names from the Third Cambridge Radio Survey Catalog that begin with “3C,” while others have a “W” number, from the Westerlund catalog. And there are others, too numerous to discuss here.
© 2002-2005 American Museum of Natural History
Last Modified: 2007-12-19 by Brian Abbott