Huge rivers of stars swirl across the Milky Approach, reducing towards the present of our galaxy’s halo in a posh gravitational dance. In response to a brand new examine of those so-called stellar streams, their offbeat orbits could be the key to uncovering the troves of invisible darkish matter lurking inside our galaxy.
Within the examine — which was accepted to be revealed within the Astrophysical Journal and is offered to learn on the preprint database arXiv.org — a global staff of astronomers used observations from two telescopes to map the orbits, velocities and compositions of 12 stellar streams crisscrossing the Milky Approach.
Stellar streams are the remnants of historic collisions between the Milky Approach and smaller neighboring star clusters; when these petite neighbors are available in contact with the comparatively large Milky Approach, our galaxy’s gravity tugs and warps them, typically pulling them into spaghettified strands that orbit the fringes of our galaxy.
The staff used laptop fashions to unwind these stretched-out streams and decide the place they originated. Based mostly on the velocity and composition of the celebrities in every stream, the staff discovered that six of the streams got here from close by dwarf galaxies (small galaxies containing as much as a number of billion stars), whereas the opposite six originated from globular clusters (a lot smaller gravitational-bound our bodies that include up to a couple hundreds stars).
“This examine offers us a snapshot of the Milky Approach’s feeding habits, similar to what sorts of smaller stellar techniques it ‘eats’,” lead examine writer Ting Li, a professor of astronomy and astrophysics on the College of Toronto stated in an announcement.
Nevertheless, that is not all of the analysis revealed. In charting the orbital paths of those 12 stellar streams, the researchers discovered that the streams moved in ways in which the gravity of the Milky Approach alone couldn’t clarify. The streams’ orbits look like influenced by invisible clumps of darkish matter — a non-luminous substance that scientists suspect accounts for about 85% of all matter within the universe.
“Consider a Christmas tree,” examine co-author Geraint Lewis of the College of Sydney stated within the assertion. “On a darkish night time, we see the Christmas lights, however not the tree they’re wrapped round. However the form of the lights reveals the form of the tree. It’s the identical with stellar streams — their orbits reveal the darkish matter.”
Researchers have detected greater than 60 stellar streams swirling across the Milky Solution to date, however they’ve by no means mapped this a lot of them on the identical time, the researchers added. By learning the motion of a number of streams on the identical time, the invisible distribution of darkish matter within the Milky Approach turns into simpler to pinpoint.
This examine — a part of the Southern Stellar Stream Spectroscopic Survey (S5), a program devoted to measuring the properties of stellar streams within the Milky Approach — will hopefully function a springboard to additional discoveries that assist unveil the darkish matter that underpins our galaxy.
Initially revealed on Dwell Science.