Milky Way is an amazing and vast galaxy, it is home to our solar system and millions of stars, which revolve around it at incredible speeds. In its center it hides a supermassive black hole, which is 4 million times more massive than our sun.
But no matter how brilliant, or massive, in our universe everything is mortal, this notion is not just limited to organic lifeforms but it also applies to nearly all of the cosmos. Moons, Planets and even the massive and brilliant stars which lit our night sky, are bound to die. In fact, the biggest and brightest stars are the ones, that live the shortest lives among stars. They consume all the fuel they have within a few million years, then explode as brilliant supernovae, which ends their life as star. They don't just vanish after death, their corpses haunt the galaxy for eternity, with their outer layers blasted away by the force of the explosion, these corpses or cores, either enter the afterlife as extremely compact neutron stars, or, collapse on themselves and form black holes. these tiny, dark remnants of stars, are scattered around our galaxy. Making The Milky Way a gigantic graveyard. where stars evolve over billions of years, burn up, and eventually perish. Scientists refer to the drifting remnants of these ancient stars as the "galactic underworld," which has kept the most of its mysteries hidden until now.
These neutron star and small black holes were once massive stars, more than eight times larger than our sun. astronomer David Sweeney and his colleagues at the University of Sydney virtually reversed time, to see how and when these early stars were born, lived and died. By analyzing and determining the time of birth, and the evolutionary course of dead stars scattered across the galaxy, they created the first digital map of the galactic underworld. What they found was astonishing, the map revealed a sprawling necropolis three times the Milky Way's height.
But Why did it take so long to find these ancient tombs of our galaxy?
The Milky Way was only beginning to form, when these early stars were born, and it looked quite different from the galaxy we know today, so different, that even its spiral arms were still taking shape. Due to which, it was difficult to even predict, where to look for these ancient elusive black holes and neutron stars, as compared to younger ones, which are scattered across the current Milky Way.
The new map not only indicates, where the remnants of these old stars could be lurking, but also, that around a third of the remnants have either been, or are in the process of being expelled from the galaxy. The massive kinetic energy of supernovae explosion, expels these long-dead stars into a halo around the visible Milky Way. Supernovas release enormous, but random amount of energy that can accelerate gas and dust, to millions of kilometers in a matter of minutes. The randomness of released energy made it extremely difficult for scientists, to predict the trajectory of dead star after it goes supernova. Interestingly, 30 percent of these dark objects, have been completely ejected from the galaxy. Which means, it is possible that many neutron stars and black holes, could have been flung into the dark intergalactic void, where they trek through space as rogue intergalactic objects.
The maps also reveal that, the distribution and structure of these small, dead star remnants are essentially different, compared to the structure of visible galaxy. In comparison to the Milky Way, this dark graveyard of stars is more puffed out.
There is still much more to be discovered about this massive galactic underworld. Scientists are developing new technologies to find out more about the elusive objects, hiding inside this dark realm of space. Scientists are hopeful that the 'galactic underworld' will not be able to stay shrouded in mystery for very much longer.
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