How the speed demons of the universe tell us something about the Milky Way

The quickest stars within the Milky Way hurtle alongside at over a thousand kilometers per second. Ph.D. candidate Fraser Evans has performed analysis into these elusive hypervelocity stars and found that they’ve loads to show us about black holes and supernovae, for instance.

Hypervelocity stars (HVS) are stars that transfer so quick they’ll escape the gravity of the Milky Way. In 2019, astronomers found a star—the S5-HVS1—which covers an astounding 1,755 kilometers per second. Dozens of those stars have since been discovered. However there are most likely a couple of thousand of them inside our galaxy.

Tens of millions of pretend stars

Evans used pc simulations to eject tens of millions of pretend hypervelocity stars via the Milky Way. He needed to get a greater understanding of the place they and their velocity come from.

“To make the precise computer simulations, we used quite a lot of knowledge from the Gaia space telescope, which has mapped a formidable two billion stars in our Milky Way,” says Evans. His analysis outcomes will make it simpler to seek out hypervelocity stars sooner or later.

Black holes and supernovae

However why is it so necessary for astronomers to seek out out extra about these velocity demons? “We are able to assume with pretty nice certainty that a few of the hypervelocity stars which have now been found have been ejected following a gravitational encounter with the huge black hole within the heart of the Milky Way: Sagittarius A*. We see an analogous impact within the Massive Magellanic Cloud, one other galaxy that we now have purpose to imagine additionally accommodates a black hole.” In the precise circumstances supernovae—exploding stars—may additionally eject hypervelocity stars.

“The celebrities that flip into supernovae are extremely uncommon in our Milky Way and the occasion is so short-lived that it’s tough to measure. Added to that, there are such a lot of stars and a lot dust flying round Sagittarius A* that we will not correctly see what’s going on there,” Evans explains. “Some hypervelocity stars are flying in additional seen components of space and might inform us extra about the place they arrive from. For instance, in regards to the gravity of black holes or the quantity of power a supernova produces.”

Though Evans had no explicit ambition to change into an astronomer as a toddler, his research and analysis have left him fascinated by hypervelocity stars.

“They’re such cool objects. A thousand kilometers per second is extraordinarily quick. You can fly all over the world in underneath a minute. Additionally they have a narrative to inform about processes within the universe about which we all know little and nonetheless have a lot to find.”