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Supernova, the Death of a Star

A Supernova is what happens to a star when it comes to the end of its life. The plural of a Supernova is officially Supernovae but you can get away with calling them Supernovas. Once the Star has finished burning its fuel, it will die and become either a black hole or a planetary nebula such as M1 - Crab Nebula in Taurus the Bull and M57 - Ring Nebula in Lyra. The term planetary is a misnomer, there aren't any planets, just a white dwarf/neutron star at the centre and a huge gas cloud surrounding it. They should not be confused with a Nova. A Nova is a sudden cataclysmic explosion in a white dwarf. A Supernova happens before a star becomes a white dwarf. When a star goes supernova, it produces more energy than at any single time in its history. Its brightness will outshine anything nearby.

There are a number of types of Supernovae, the main two are known as Type Ia and Type II. As you've probably worked out, there are Type Ib and Ic but they are not as major as the ones mentioned before. The following has been taken from N.A.S.A's page on the subject.

Type 1a Supernova

These result from some binary star systems in which a carbon-oxygen white dwarf is accreting matter from a companion. (What kind of companion star is best suited to produce Type Ia supernovae is hotly debated.) In a popular scenario, so much mass piles up on the white dwarf that its core reaches a critical density of 2 x 109 g/cm3. This is enough to result in an uncontrolled fusion of carbon and oxygen, thus detonating the star.

Type II Supernova

A lot simpler to understand that the Type 1a. The Type II is a solo star which just simply runs out of fuel and blows itself up.

After the supernova, the remnants either become a nebula if the original size was less than five Solar masses or a black hole if the star was a supergiant before it started its way out. When a star has run out, it will loose the energy required to hold itself as a star and grow. When the Sun runs out of energy, it will grow and its outer edge will expand past the Earth. All life on Earth will have disappeared long before the Sun has expanded that big.

There is a theory that the planetary nebula could collapse back on itself and produce another Sun and solar system.


An Unnova is a star that is not able to go supernova, instead it collapses and disappears. Whilst the convention for a dying star is to grow into a supergiant and then explode, there is the theory that a star might not be able to cause a supernova. The Unnova is when the star will just collapse into a black hole.

Unnova's are also referred to as Failed Supernovas because they did get there. When a supernova occurs, it can destroy its solar system but with an Unnova, the solar system can be unaffected. If the Sun was to go Unnova, the planets would survive. The Earth would be in perpetual darkness and overtime, it would get cold. It would be cold immediately because of the heat from the iron core but over time, it'll get cold. Life on the surface would die and any humans would have to move off the planet or live underground where they'd be able to create warmth and live.

What is the brightest Supernova currently?

The current record holder of the brightest supernova goes to one imaginatively named SN 2005ap, It is located in the constellation of Coma Berenices. It was so bright that at its peak, it was a bright as 50 billion Suns. It was probably caused by the death of a star that was had at least 150 solar masses.1 It is a Type II Supernova and was located some 4.7 Billion Light Years away from the Earth and although it was bright, it couldn't be seen unaided from the Earth.

Pulsars and Neutron Stars

When a star goes supernova, it can produce a planetary nebula with a Neutron star at the centre of it. A neutron star is a star that is made predominantly of neutrons which are particles that have zero electrical charge and are ever so slightly bigger than a proton. A neutron star can spin round firing off gamma rays and thus be known as a pulsar. pulsars were first believed to be a signal from an alien race on a far off planet but scientists downgraded their excitement to what they are now.

Death of a Star, Birth of Life

It is said that a star will use up all its hydrogen fuel first by turning hydrogen into helium. Once it has used up all its hydrogen, it will then turn helium into Lithium and so and so forth. However, a star will stop once the only fuel it has left is iron which is number 26 (FE) on the Periodic table. The other elements such as Gold, Mercury and Uranium can only be created in the furnace of a supernova. They say that a star long ago exploded close by and the remnants of the star were captured that then became our planets and us. Our matter, the stuff we are made of existed since the beginning of the Big Bang and has been recycled through the ages.

Third Generation Sun

The Sun has sometimes been referred to as a third generation star. The universe is seen as being 13.8 billion years old, the Sun is a mere 4.5 billion years old. Therefore since the beginning of the universe to the creation of the Sun is about 9.3 billion years. The Sun has about another 5 billions years to go, although life only has another 1 billion years left before the Sun becomes too hot to survive and water evaporates away. It is said that before the Sun, there were stars that had been and gone and had been its predecessors. The left overs of the previous stars became materials for the Sun when those earlier stars went supernova.

When our Sun goes pop in about 5 billion years, it will have expanded to beyond Earth. The outer planets will not be swallowed up by the expanding Sun but they will be changed forever. The outer planets will loose their atmospheres and if they had a rocky interior, it will not be exposed and just be just another asteroid in space.

A Supernova threat to the Earth

An exploding star that is within 30 light years of the Earth were to explode, it would have devastating consequences for the Earth. The Gamma Ray burst that gets fired out when the explosion occurs will when it arrives here blow away our atmosphere and scorch the planet. A safe distance from a supernova has been calculated at being about 50-100 light years at which point the Gamma Ray bursts would have dissipated. The most likely star to go off is Betelgeuse in Orion and that is over 400 light years away, more than safe. That is the nearest star to our Solar System that could go pop. If the star did go pop, we would have to be in the line of fire when the bursts arrive as well. It is estimated that Betelgeuse will go pop in the next 100,000 years, a long time yet.

It has been calculated that a star goes supernova once every 100 years per galaxy. Taking into account the number of stars and the number of galaxies out there, we've actually not got anything to worry about at the moment. When the Sun goes supernova, our planet would have been long destroyed as the Sun would have melted it away. One of the reason people give why we've not had any contact with advanced civilisations is because they could have been killed by a supernova explosion.

Zombie Star

A zombie star is a hypothetical result of a supernova explosion that instead of dispersing its stellar matter, it leaves behind a remnant star. They are thought to be the results of a Type 1ax explosion that is similar to a Type I but the main difference is that the supernova has a lower ejection velocity and lower luminosity.2. The picture below is of a supernova star system linked to potential Zombie Star in the galaxy NGC 1309 in the constellation of Eridanus. More information on this can be found at N.A.S.A..

Potential Zombie Star discovered in the Galaxy NGC 1301 in constellation of Eridanus.

White and Black Dwarfs

After the supernova explosion, a white dwarf can be the remnants of the Star. It will glow and glow for millions and billions of years. It will continue to glow until its fuel has run out but it won't supernova again. The White Dwarf will simply fade into a black dwarf then over more time, the star will dissipate into nothing. The Universe is too young for any of these black dwarfs to exist and only hypothetical grounded in science.

M1 - Crab Nebula Supernova Remnant

M1 - Crab Nebula

Despite its name, it is not classed as being part of the Cancer constellation, however it is in the nearby constellation of Taurus. It is believed to have been first recorded as a supernova in 1054 by Chinese astronomers of that time. At the centre of the Nebula is a Neutron Star that 28-30 km across which rotates about 30 times a second.

M1 - Crab Nebula 0 Supernova Remnant

M57 - Ring Nebula

The Ring Nebula is a supernova remnant that can be seen in the northern constellation of Lyra. It was first discovered in 1779 by French Astronomer Antoine Darquier de Pellepoix but was first catalogued by Charles Messier who compiled the Messier Catalog.

SN W49bSupernova RemnantAquila
Veil NebulaSupernova RemnantCygnus
SN1987aSupernova RemnantDorado
DEM L241Supernova RemnantDorado
Jellyfish Nebula (IC443)Supernova RemnantGemini
Asassn-15lhSupernova RemnantIndus
Ring Nebula (M57, NGC6720)Supernova RemnantLyra
RCW103Supernova RemnantNorma
Lobster Nebula (NGC6357)Supernova RemnantScorpius
Crab Nebula (M1, NGC1952)Supernova RemnantTaurus

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