Some mind-blowing violence for this evenings’ deep sky viewing. The shredded remains of an exploded star.

What actually happened during the Vela Supernova whose remnant is imaged here ? ….. and if you want to get very rich, read on.

The Vela Supernova Remnant spans the night sky some 16 full moons in angular diameter in the constellation Vela (the Sails). Captured with 9 hours of exposure last Saturday and Sunday night from Seacliff (Adelaide) using narrowband Hydrogen Alpha and Oxygen III filters (540 x 1-minute subframes over 2 nights) behind a Nikkor 50mm f1.8 lens. Who needs, or what use is, a telescope when the object being imaged is this large in the night sky !

Some 11,000 years ago, just prior to the start of the Holocene, at the time of rapid glacial retreat at the end of the last ice-age, as Jericho in the Middle East was being settled by Natufian hunter-gather groups, when the ceremonial structures at Gobekli Tepe were being built in southern Turkey, and around the time that giant short-faced bears and giant ground sloths that roamed south America were going extinct ……. a supergiant star in Vela (within the orbital plane of our galaxy) with a mass of between 8-50 solar masses, was nearing the end of its short life. A high temperature-high luminosity blue supergiant star evolved to become a red supergiant during which it progressively cast off its outer gas layers in a series of convulsions as it entered the latter stages of its life cycle. These large stars typically only live for a few short million years.

Ongoing nuclear fusion reactions in the star’s core fuses hydrogen into helium, releasing tremendous amounts of energy that counter balance the star's gravity trying to collapse it in on itself (this is our sun now, in stable equilibrium of opposing forces). Once the massive star runs out of hydrogen in its core, it switches to fusion of helium, then fusion of carbon, then neon, all the way up the periodic table of elements (the elements that make up much of our bodies) until it reaches iron. Iron doesn't produce energy through fusion, so at that point there is no longer any outward nuclear pressure holding back the mass of the star from collapsing inward under gravity.

The outer edges of the star’s core collapsed inward at around 70,000 km/second, about 23% the speed of light. In just a quarter of a second, infalling material of the collapsing star rebounded off the iron core, creating a shockwave of matter that propagated outward ……. Boom, a Type II supernova, seen here around 11,000 years after the supernova event.

As this shockwave raced up through the outer more tenuous layers of the star, it compressed the gas and created exotic new elements that the original star could never form in its core. This is where we all get rich. All gold, silver, platinum and uranium and anything higher than iron on the periodic table of elements are created here in the first seconds, minutes and hours of the supernova. At this point, the Vela supernova had put out as much energy as the rest of the galaxy and its billions of stars combined, as it brightened some 100 million times to rival the moon in the Palaeolithic night sky. What a sight those last few giant ground sloths would have had !

As the supernova raced outward into the cosmos, seeding it in elements that will later support life, down in the stars core (at the inner end of the supernova explosion), matter within the iron shell of the stars core was likewise being compressed under stupendous inward pressure of the stars initial gravitational collapse in the first second of the supernova. While the starting mass of this supernova star, and hence inward gravitational pull, was not high enough to produce a black hole or singularity of infinite density, it was, nevertheless, high enough to disaggregate the very atoms themselves into their constituent sub-atomic particles of neutrons, protons and electrons, and all the while compressing the protons and electrons together to form additional neutrons. A neutron star was born in those few violent seconds. This ultra-dense compressed core of neutrons was now so dense that the original 1-2 solar mass core of the Vela star had been compressed to around 20 km diameter (the size of a city). A teaspoon of this 20 km diameter ball of neutrons at the core of the supernova would weigh around the weight of Mt Everest.

Stars like our sun, that rotate once on its axis every 27 days, are braked as they expand into red supergiants, so end up rotating evenly more slowly. Now imagine what happens when this star goes supernova. Just as a ballerina spins faster as she pulls in her arms, so the supergiant red star that may have had a diameter equivalent to the orbit of Mars, spins up in a few seconds as it suddenly collapses to around 20 km diameter. Its rotational velocity goes through the roof as it revs up. The Vela neutron star (the compressed core of the exploded star) that lies at the centre of this supernova remnant is currently spinning like a madman at around 11 revolutions per second. It is also a pulsar, beaming focussed jets of particles from its poles as it rotates at 11 revolutions per second. In fact this neutron star that is the remains of this beautiful supernova remnant, is located and visible just a smidgeon below and left of the centre of this image.

Blue hues are clouds of oxygen gas racing outward whilst the red hues are clouds of hydrogen gas.

There is certainly some interesting physics going on in this image, and to think there is one of these supernova is going off somewhere in the cosmos every 10 seconds.