The whitish Way has been known to be snacking on its neighbors for 1000000000000 of years , slowly but surely merge with several of the many midget beetleweed that environ our galaxy . The leftover of such interaction can be seen today in the human body of starring streams wrapping around the wandflower like ribbons .
A newly discovered " ribbon " is the Jhelum stellar flow . Due to its location in the sky , astronomers considered this current to be part of a collision between the Milky Way and the Gaia - Enceladus - Sausage dwarf galaxy , recall to have occurred between eight and 11 billion years ago .
Now new observation have uncover that Jhelum does n’t come from the Sausage dwarf galaxy after all . Astronomers were capable to study the light spectrum of stars in the Jhelum current , which gave them an idea of what the asterisk are made of . sensation that work together will have a interchangeable composition . This was tracked using the Apache Point Observatory Galactic Evolution Explorer ( APOGEE ) survey , part of the Sloan Digital Sky Survey ( SDSS ) .
The composing allow take the sensation that work and belong together . By combining this with detailed data about their spatial relation and motion from theEuropean Space Agency ’s Gaia , the team show that the Jhelum stream did not match the other grounds of the Sausage collision . Its parentage was elsewhere .
" Like fingerprints or tag , the chemic properties of stars in a stream can be used to tell them apart from other streams – but more than that , having the chemical makeup , positions and gesture together is fantastically worthful , and just goes to show the welfare of combining APOGEE and Gaia , " senior author Professor Allyson Sheffield , from LaGuardia Community College , allege in astatement .
The Jhelum flow is only observable from the southern cerebral hemisphere so it was thanks to the southerly APOGEE instrument ( APOGEE-2 ) coming online that the team was able to use to distinguish the correct stars and then work out who were the real fellow member of the stream .
" assess the tracks , or celestial orbit of stars in the stream allows us to almost turn back the cosmic clock , and let out where the flow itself may have come from , " bestow co - author Aidan Subrahimovic , an astrophysics student at City University of New York .
Researchers ca n’t link up the Jhelum stream to any specific unification with a dwarf Galax urceolata or a globular cluster and so its origin currently remain unknown . However , succeeding body of work might help researcher witness an response to the origin of this and other stellar streams in our Milky Way .
