The aboriginal all-embracing age-map of the Milky Way shows that a aeon of brilliant accumulation abiding about 4 billion years created the circuitous anatomy at the affection of our galaxy. The after-effects will be presented by Marina Rejkuba at the European Week of Astronomy and Space Science (EWASS) in Liverpool on Tuesday, 3rd April.
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The Milky Way is a circling galaxy with a appendage at the centre, bags of ablaze years in diameter, that contains about a division of the absolute accumulation of stars. Antecedent studies accept apparent that the appendage hosts two components: a citizenry of metal-poor stars that accept a all-around distribution, and a citizenry of metal-rich stars that anatomy an continued bar with a “waist,” like an x or a bi-lobed peanut. However, analyses of the ages of the stars to date accept produced adverse results. Now, an all-embracing aggregation led by astronomers from the European Southern Observatory (ESO) accept analysed the colour, accuracy and ashen advice on allure of alone stars to aftermath the age-map of the Milky Way.
The aggregation accept acclimated apish and empiric abstracts for millions of stars from the VISTA Variables in the Via Lactea (VVV) bittersweet assay of the close Milky Way and compared them with abstracts of the metal agreeable of about 6000 stars beyond the close appendage from a spectroscopic assay agitated out with the GIRAFFE/FLAMES spectrograph on the ESO Very Ample Telescope (GIBS).
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Rejkuba says: “We analysed the colour and accuracy of stars to acquisition those that accept aloof accomplished the point of backbreaking their hydrogen fuel-burning in the core, which is a acute age indicator. Our allegation were not constant with a absolutely old Milky Way bulge, but crave brilliant accumulation abiding about 4 billion years and starting about 11 billion years ago. The youngest stars that we see are at atomic 7 billion years old, which is earlier than some antecedent studies had suggested.”
The after-effects presented are based on the assay of three areas of the VVV bittersweet map, which, combined, accomplish up the better breadth advised so far in the Milky Way bulge. In all three areas, the allegation on the age ambit of the stars are consistent.
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Francisco Surot Madrid, the co-lead columnist of the study, says: “Previous studies accept told us that the metal-rich stars in the bar are acceptable to be the youngest stars. Whilst we can’t disentangle which brilliant belongs to the bar/peanut or the apple basic in the abstracts we are using, our after-effects acquaint us that the bar was already formed about 7 billion years ago and there were no ample amounts of gas flood and basic stars forth the bar afterwards that.”
The ultimate ambition of this activity is the architecture of a map of the brilliant accumulation history of the absolute Milky Way bulge.
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Co-lead author, Elena Valenti, says: “The final map will appearance us the brilliant accumulation amount as a action of both age and metallicity for the stars beyond the bulge. This will be an important additive in cogent the complete adventure of the accumulation of the Milky Way bulge.”
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