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Supernova Trail

Supernova

thumb|250px|right|[Supernova remnant|Remnant of Kepler's Supernova, SN 1604.] Supernova refers to several types of stellar explosions that produce extremely bright objects that decline to invisibility over weeks or months. There are two possible routes to this end: either a massive star may cease to generate fusion energy in its core and collapse inward under the force of its own gravity, or a white dwarf star may accumulate material from a companion star until it reaches a critical mass and undergoes a thermonuclear explosion. In either case, the resulting supernova explosion expels much or all of the stellar material with great force. The explosion drives a blast wave into the surrounding space, forming a supernova remnant. One famous example of this process is the remnant of SN 1604, shown at right. Supernova explosions are the main source of all the elements heavier than oxygen, and they are the only source of many important elements. For example, all the calcium in our bones and all the iron in our hemoglobin were synthesized in a supernova explosion, billions of years ago. Supernovae inject these heavy elements into the interstellar medium, thus enriching the molecular clouds that are the sites of stellar formation. This enrichment process is what determined the composition of the Solar System 4.5 billion years ago, and ultimately made possible the chemistry of life on Earth as we know it. Supernovae generate tremendous temperatures, and under the right conditions, the fusion reactions that take place during the peak moments of a supernova can produce some of the heaviest elements like californium. "Nova" (pl. ''novae'') is Latin for "new", referring to what appears to be a very bright new star shining in the celestial sphere; the prefix "super" distinguishes this from an ordinary nova, which also involves a star increasing in brightness, though to a lesser extent and through a different mechanism. However, it is misleading to consider a supernova as

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Supernova

First line

The first line seems to imply that Supernovae result in the formation of new stars. It should state that it forms a bright object that some may have interpreted as a "new" star in the past. The confusion is particularly troubling since Supernova are actually a result of the stellar dying process. :That's a good point. I made some edits to the article. Etymology is now in a separate paragraph; the intro now focuses on what a supernova ''is'', rather than on the origin of the name. -- Curps 21:03, 12 Mar 2005 (UTC) Unfortunately, the intro now describes only Type II SNe, and ignores Type I (WD thermonuclear) SNe. It also probably should not focus on the star formation aspect, as that is both somewhat controversial (eg see Hester et al. 2004, Science) and secondary to the phenomenon. Mordecai-Mark Mac Low 00:58, 30 Mar 2005 (UTC) I have grabbed the relevant text from supernova remnant, which was more accurate. The deleted text is here Mordecai-Mark Mac Low 17:17, 2 Apr 2005 (UTC): :There are at least two different types of supernova which have different triggering mechanisms which are described in detail below. However, the general pattern of a supernova explosion is that it occurs when a star finally exhausts its thermonuclear fuel, the delicate virial balance between energetic thermal expansion due to fusion and compression due to gravity is lost. I also rewrote the rest of the introduction:

removed triggered star formation (see my comments above) and emphasized heavy element production, which was the real point of that paragraph

moved the definition of "foe" to its own entry, which was only a stub. This unit is only used by some specialists in the subject (I have been working on SNe my entire career, and had never encountered it; it shows up only three or four times in the last five years in a full text search on NASA ADS). Mordecai-Mark Mac Low 17:17, 2 Apr 2005 (UTC)

Supernovas or Supernovae?

Which is the

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Supernova Remnant

thumb|250px|right|The Crab Nebula is an expanding cloud of gas created by the 1054 supernova. thumb|250px|right|Remnant of Kepler's Supernova, SN 1604. supernova remnant]] A supernova remnant (SNR) is made up of the materials left behind by the gigantic explosion of a star in a supernova. There are two possible routes to this end: either a massive star may cease to generate fusion energy in its core, and collapse inward under the force of its own gravity, or a white dwarf star may accumulate material from a companion star until it reaches a critical mass and undergoes a thermonuclear explosion. In either case, the resulting supernova explosion expels much or all of the stellar material with great force. In the case of a massive-star explosion, the core of the star may collapse so rapidly that it forms a sort of extremely compact (degenerate) matter. This compact object, which may be a neutron star or a black hole, is referred to as a compact supernova remnant. For both massive and white-dwarf stellar progenitors, the outermost layers of the star will be blown off by the force of the explosion into an expanding cloud of dust and gas. The shock wave and ejected material expanding from this explosion, and the interstellar material it sweeps up along the way, are called a diffuse supernova remnant. Perhaps the most famous and best-observed supernova remnant is SN 1987A, the newly formed remnant of a supernova in the Large Magellanic Cloud. A few other well-known supernova remnants are the Crab Nebula, a remnant of a relatively recent explosion (AD 1054); Tycho, a remnant named after Tycho Brahe, who recorded the brightness of its original explosion (AD 1572); and Kepler's SNR (SN 1604), named after Johannes Kepler.

Other resources

http://www.mrao.cam.ac.uk/surveys/snrs/ SNR Catalogue(D. A. Green Cambridge University)

http://agile.gsfc.nasa.gov/docs/objects/snrs/snrstext.html NASA: Introduction to Supernova Remnants.

http://www.site.uottawa.ca:4321/astronomy/index.html#novaremnant_table

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Supernova Remnant

Actually, the proper English is either, "it ceases" or "it may cease," likewise "it undergoes" or "it may undergo". We need to either change it back or eliminate the "may". :) -- April I slipped on the "cease" i changed it back. However, i don't agree with the other. I don't see the "may" of "may accumulate" affecting the "reaches" and "undergoes". I might be wrong, but if it has to be changed, both reaches and undergoes must change. AstroNomer

Agreed, that's right. dang, this grammar stuff is tricky. :) -- April

Redo/expand this page

I'll redo, expand this page when I get a moment, it should really have some stuff on the Sigma-D relation and the Selection effects etc. Could do with links to Molonglo Observatory Synthesis Telescope, Parkes 64m Telescope and Effesberg, since they are the big contributors to finding SNRs (radio sky surveys). Also Dominion Radio Astrophysical Observatory would be good. Am newbie so not sure how to do much yet, but don't mind if anyone jumps in and adds those first. Will write some more sciency stuff on it laters.

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Supernova Trail