Astronomers have discovered some of the most ancient stars in the Milky Way and track their position and motions . This selective information has provided newfangled insights into how our very own galaxy came to be 13 billion years ago . The very heart of theMilky Wayhas now been uncovered .
The researchers recently publisheda elaborate understanding of how our beetleweed evolvedin its most exciting and chaotic period , roughly 11 billion geezerhood ago . They were able-bodied to track extragalactic nebula collisions that radically changed the Milky Way , bringing young virtuoso and gas but also heave the disk of our wandflower where the spiral arms ( including the one containing the solar system ) are located .
The thin disk is 105,000 light - years across and no more than 1,500 wakeful - years thick and still experiences star formation . There ’s also a thick record , enveloping much of the slender disk but with less density . At the plaza of the Milky Way , there is a bar - like structure that tends to host most of the older stars .
The simplified feature of the Milky Way seen from the side in this artist’s impression. Image Credit: Stefan Payne-Wardenaar / MPIA
However , the earlier body of work indicate that the buddy-buddy disk was there from almost the very first . We ca n’t simply point to the core and say that was the beginning of the Milky Way . feigning suggested , based on our best understanding of the history of our galaxy , that three or four protogalaxies must have formed near each other . They interacted and merged in a compact core of no more than a few thousand unclouded - years aside . That ’s the heart upon which , through merger and flatulence menstruation , the whole Milky Way formed around .
To hunt for this ancient grouping , the team had to utilise data from theEuropean Space Agency ’s Gaia Satelliteto study red titan . These stars are very bright , so it allow for the team to see further – but that is only half the battle . To understand the long time of a star , an astronomer looks at how " polluted " it is . The very first contemporaries of asterisk was made just by atomic number 1 and atomic number 2 , and as they fit supernova they spread all the other element ( advert to as the " metals " in astronomy ) , so each new generation has higher and gamy metallicity .
Gaia data is vast but not passing detailed when it come to educe metallicity , so the squad trained a machine learning algorithm to go through a specific subset of Gaia data point and analyze it to make it better . The subset had already well - know metallicity from the APOGEE program , so when theartificial intelligencelearned how to extract the proper answer it was deployed on the full Gaia data set of over two million red hulk .
From there , the team was capable to find the metal - poorest , most ancient stars , all older than 12.5 billion years and all within 30,000 light - eld from the center of the Milky Way . These object were there in the early years and could severalize us much more .
The team hopes to analyse them in more particular to empathize their chemic evolution and their movement . This could answer more questions about the formation of the Milky Way , including how many protogalaxies clumped and merged together .
The challenging sketch was put out inThe Astrophysical Journal .
