“Australian researchers in OzGrav have a played a major role in this discovery and, indeed, in all gravitational wave discoveries since the first detection in 2015. Now, Australian scientists (working as part of the LIGO/VIRGO collaboration) have for the first time used gravitational waves to directly observe the birth of a black hole with a resultant mass of around 150 suns, challenging existing models of the lives of big stars before they become black holes. There couldn’t have been stars this big to create them individually, so scientists have been trying to work out if they accumulated from smaller, stellar-mass sized black holes, and if so, why isn’t there a third category of objects that sits between – the Intermediate-Mass Black Holes? These two distinct populations are classed based on their observed masses, and immediately showcase a fascinating question – how did supermassive blackholes, whose mass range is millions or billions of times that of our Sun, come to be? It’s interesting to note that the entire 25 solar masses doesn’t become the black hole – a lot of that material is blown away and only a few solar masses in the collapsed core becomes the belly of the beast.īy understanding this evolutionary model of how stars end their lives, scientists are able to then use this information (along with a variety of other data) to start to calculate the upper limits of how big stars can be based solely on the type of remnant object observed, and from this also determine the evolutionary formation of such remnant objects.Īnd here is where it gets really interesting – even more so beyond the fact that we can now observe black holes (an achievement upon itself that should be marvelled at).īy studying a variety of different sources of information (such as gravitational-wave data, x-ray observations, Galaxies, binary star systems, etc.), astrophysicists have been able to classify different categories of black holes: those that are the remnant product of stellar supernova explosions, and those which reside in the centre of galaxies, known as supermassive black holes. And extremely massive stars (which contain over 25 solar masses of materials) will form a black hole. High mass stars (with a range of 9 – 25 solar masses) will leave behind a neutron star. Low mass stars like our Sun will end up as white dwarfs. Which pathway a star ends up following is dependent entirely on its mass. It keeps going and going, until all the material – with a lower limit of about 3 times the mass of our Sun – is squeezed into a point so small, a point with such infinite density, that it causes the very fabric of space-time to curve in on itself, not even allowing light to escape. Following their violent demise and destruction, their seeding of the Universe with new heavy elements, and their short, yet brilliant lives (which only span a few million years) – the cores of these big ones keep collapsing inwards. The cores of these ones however go the other way – they collapse inwards and form mind boggling compact objects – each no larger than a small city – yet spinning hundreds of times per second on its axis, possessing a magnetic field billions of times stronger than that of Earth’s and having densities so large, that a single teaspoon of this new remnant would weigh as much as a cube of Earth’s crust with dimensions of 800m X 800m X 800m.Įven bigger stars don’t stop there, though. Other stars, somewhat larger, will explode like one of those big firecrackers that tears through the night sky with an array of incendiary colours, on New Year’s Eve as the clock strikes 12 - blasting the majority of their own stellar materials out into space at violent speeds, further spreading the polluting tide of heavier elements out into the cosmos. They’ll eventually pollute the surrounding region of space with all the new elements they’ve churned in their cores over their 10-billion year lifetimes, billowing out the material and allowing the next generation of stars to use it when it is their time to start the cycle over again.Ī lifeless white-hot cinder core of the star that gave life and light to the humans and many other species for all those years, will be the only thing left from this time in our neighbourhood in space. Some stars, like our Sun, will huff and puff their outer layers as they near the end of their lives, departing in a relatively simple and quiet manner. But not all stars are going to go off with a bang when they die. When you think about stars ending their life in the Universe, the movies tell us they explode in brilliant blasts that create huge shockwaves, that sweep and destroy over any planets nearby.
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