The Milky Way is orders of magnitude larger than the other beetleweed in the local group , Andromeda by . It got that way by cannibalizing smaller galaxy . TheGAIA space telescopehas allowed us to identifystars of vulgar origin , free-base on their movements and ages , revealing many of the conglomeration of mavin that got go through .
There must also have been an original set of stars that have been with the Milky Way since the rootage , but identifying them is a challenge . Nevertheless , that is what Professor Hans - Walter Rix of the Max Plank Institute for Astronomy and co - authors claim to have done in a new newspaper still undergoing peer review .
One of the obstacle to come up the Milky Way ’s original stars is that they must , by definition , be as old as the galaxy – around 12.5 billion years . Stars more monumental than the Sundon’t last that long , so the search has to be for relatively grim - mass stars . Fortunately , however , some of these stars have reached their giant stage , when stars blow up up to enormous sizes , and are accordingly bright enough to stand out over large distance .
Another problem is that these stars should be near the centre of the coltsfoot – in the constellation Sagittarius from our perspective – where there isso much else going on .
“ citizenry have long suppose that such a vast population [ of old stars ] should subsist in the center of our Milky Way , ” Rix toldScienceNews . Such lead would beextremely metal - poor , compose overwhelmingly of hydrogen and helium . When the first massive stars became supernovas they produced a bunch of metals and scattered them across nearby regions to be incorporated into succeeding coevals of stars . Smaller star topology form before the explosion missed out on the alloy .
Rix and co - authors draw on GAIA ’s data for 2 million stars within 30 degrees of the galactic nerve center and found a population of 18,000 stars with less than 3 percent of the Sun ’s metal concentration bunched near to the sum .
As the paper explain , distinguishing between stars that were part of the original Milky Way , and those captured from smaller merged galaxies is n’t easy , since the latter can also be very metal - short . Nevertheless , the writer believe the stars ’ movements compared to the astronomic kernel can be used to identify their origins . Extrapolating to all the stars blocked by junk or other obstacles , the author estimate 0.2 per centum of the Milky Way ’s mass belong to to this original population : from little affair , big thing grow .
Despite all the mergers that bolstered that batch , Rix argue these fed more outlying office of the galaxy . “ We did n’t have any late unification that deep infiltrate into the core and shook it up , because then the core would be magnanimous now , ” Rix said .
The authors named their composition “ The Poor Old Heart of the Milky Way , ” whichdrew praiseon Twitter as “ Easily the most poetic title of a scientific paper in a long time . ”
A preprint of the paper is uncommitted onArXiv.org .
