SN 1572
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X-ray image of the SN 1572 remnant |
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| Observation data (Epoch ?) |
||
|---|---|---|
| Supernova type | Type Ia | |
| Remnant type | Nebula | |
| Host Galaxy | Milky Way | |
| Constellation | Cassiopeia | |
| Right ascension | 0h 25.3m | |
| Declination | +64° 09′ | |
| Galactic coordinates |
G.120.1+1.4 | |
| Discovery Date | November 1572 | |
| Peak magnitude (V) | -4 | |
| Physical characteristics | ||
| Progenitor | Unknown | |
| Progenitor type | Unknown | |
| Colour (B-V) | Unknown | |
| Notable features | ||
SN 1572 or Tycho's Nova was a supernova in the constellation Cassiopeia, one of the eight supernovae visible to the naked eye (so far). It was first observed on November 11, 1572 by Tycho Brahe, when it was brighter than Venus. In March 1574 its brightness fell below visibility with the naked eye.
Tycho Brahe may not have been the first to notice the supernova; it was probably Wolfgang Schuler, who first saw it on November 6, 1572. The Italian astronomer Francesco Maurolico may also have spotted it before Brahe.
The supernova remnant was discovered in the 1960s by scientists at the Mount Palomar telescope as a very faint nebula. It was later photographed by a telescope on the international ROSAT spacecraft. The supernova was probably of Type Ia, in which a white dwarf star has accreted matter from a companion until it reaches the Chandrasekhar limit and explodes. This type of supernova does not typically create the spectacular nebula more typical of Type II supernovas, such as SN 1054 which created the Crab Nebula. A shell of gas is still expanding from its center at about 9,000 km/s.
In October 2004, a letter in Nature reported the discovery of a G2 star, similar in type to our own Sun. It is thought to be the companion star that contributed mass to the white dwarf that ultimately resulted in the supernova. A subsequent study, published in March 2005, revealed further details about this star: labeled Tycho G, it was likely a main sequence star or subgiant prior to the explosion, but had some of its mass stripped away and its outer layers shock-heated from the effects of the supernova. Tycho G's current velocity is perhaps the strongest evidence that it was the companion star to the white dwarf, as it is traveling at a rate of 136 km/s, which is more than forty times faster than the mean velocity of other stars in its stellar neighbourhood.
SN 1572 is associated with the radio source G.120·1+1·4. It has an apparent diameter of 3.7 arc minutes, and is located approximately 7,500 light years from our Solar system.
