1 – Supernova and Neutron Stars

Supernova and Neutron Stars
Stellar evolution. Life cycle of a star. from Stellar nursery and Red giant, to Black and White dwarfs, Planetary nebula, Supernova, Pulsar, Neutron star, and Black hole

It is always fascinating to look up and see the marvels of nature. The most astonishing of all are Supernova and Neutron Stars. They are the forerunners of the most mysterious Steller object “The Black Holes“.

Supernova and Neutron Stars Shining

When the largest of stars explode, for a brief moment that Supernova and Neutron Stars will outshine every star in their galaxy combined, unleashing energies that will shred their orbiting planets and might sterilize thousands of neighboring solar systems. Of course Supernovae are already an engine of creation, and are well known for their role in creating all the heavier elements we need to live from the hydrogen and helium forged shortly after the Big Bang.

But giant stars exploding is just one type of Supernova, and neither it nor the other types are the only source of those heavy elements, many of which are not even created in your typical supernova. Virtually every star in the Universe is from 8% our Sun’s Mass to 8 times our Sun’s mass, but we do have rare stars more massive than that, some more than a hundred times more massive than our Sun.

Burnt up Fuel of Supernova and Neutron Stars

Supernova and Neutron Stars are easy to see as they are many thousands of times brighter than our own Sun, some being even more than a million times brighter. They are not thousands or millions of times more massive than our Sun though, and this is part of why they are few in number.

Very large stars burn their fuel up far faster and less efficiently than most stars and they die quickly. Indeed the biggest might only live a million years, while the smallest stars might live over a trillion, and in comparison the one is a dim campfire that will burn all night while the other a truckload of TNT set off in under a second.

Such giant stars might end in a fiery explosion but compared to a red dwarf, their entire lifetime is essentially a brief fiery explosion. Such being the case it results in an assumption that you would never colonize star systems too close to a giant star that was a supernova candidate.

Life Time Relativity of Stars

We need to remember that everything is relative, and we use the term ‘astronomical’ to talk about something being huge or hugely improbable precisely because the astronomical scale is so insanely big compared to our own existence.

If someone told me that they had two options and only two options, to settle a giant star set to die in a million years, along with its dozens of neighbors, or to stay home and colonize nothing, then even knowing they would die, even if I was certain that was the only outcome, I would still tell them to ship out to that supergiant and its endangered neighbors, because a million years is as long as humanity has even been around and a hundred times longer than human civilizations have truly existed.

Orange Nebula with stars on background

Understanding Life Cycle of Supernova and Neutron Stars

However, that’s not the only outcome. We must first understand why Supernova and Neutron Stars explode. First off, the notion that they burn their fuel up and explode is not really accurate. For these big stars, they are burning hydrogen into helium or helium into carbon or so on, and not just in their core. That’s simply where it happens first and fastest, and where it eventually stops.

 Once the core is turned to iron which is the end of fusion in stars. There’s no fusion going on in that core anymore when the explosion comes. Indeed the star will have come to resemble an onion, the outermost still principally made up of hydrogen, and the layers in between dominated by helium, carbon, Neon, Oxygen, Silicon and finally iron at the core.

These outer layers are what will be spread by the supernova while the iron core turns into a stellar remnant, a neutron star or black hole.

Only stars massive enough to permit silicon fusion into iron can go supernova. Though in point of fact, the silicon does not make iron at all, it makes Nickel-56 which decays into Cobalt-56 which decays into Iron-56 over the course of a few months.

The Red Giants

They expand into red giants, or red Super-giants, and undergo quite a few changes and enter a blue loop where they rise then drop in surface temperature. But at some point down in the core the carbon that’s been collecting from Helium-fusion begins fusing, and this starts the doomsday clock of about a thousand years as neon accumulates. Once it switches over to burning neon, the end is only a few years away.

For oxygen burning processes, mere months, and for silicon, mere days, as nickel accumulates and decays into iron. This big ball grows until we have a metal core of 1.4 Solar Masses, and now the sheer mass of that metal ball with no fusion to burn, to create outward pressure, and keep it apart causes that core to collapse, in mere seconds.

As Supernova and Neutron Stars collapses it picks up speed while falling inward, and therefore energy. The collisions as it falls and gains energy heat that metallic core up, emitting gamma rays that tear the iron apart into what will eventually be nothing but a Dense Ball of Neutrons, or a Neutron Star, assuming it doesn’t collapse even further into a black hole.

All of this is emitting neutrinos, tons of neutrinos, which interact so weakly they can escape this ultra-dense core to be absorbed by the outer layers of the star and begin shoving it away, initiating the Supernova. Collapse is insanely energetic and emits a lot more than neutrinos, but the sheer density of matter is now so high that nothing but a neutrino could escape.

The Neutron Star

We’re now left with a dense core near collapsing; into a Neutron Star. But too hot to do so, and we get a several-second Thermal Neutrino Blast. Most of these neutrinos exit the star without being absorbed by the upper layers, some are absorbed and continue powering the ejection of those layers. These are some reasons why a Supernova is not an ideal weapon, it is omni-directional. Most of it is neutrinos which are harmless to anything not either super-dense or super-thick, and of course it’s hard to move a star where you want it to be.

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