Bright star pulses reveal when Milky Way devoured another galaxy
New measurements suggest the Milky Way gobbled up Gaia-Enceladus when it was just a fledgling baby galaxy.
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Using asteroseismology, a way to study how stars pulse and oscillate, the team were able to determine the age of v
and revealed that it's had a long life -- it's approximately 11 billion years old, meaning it was likely born in the early years of the Milky Way's life. In addition, v Indi comes from a region of space that appears to have been affected when Gaia-Enceladus was swallowed up by the Milky Way.
That information allowed the researchers to more accurately date this huge collision of galaxies.
"Since the motion of ν Indi was affected by the Gaia-Enceladus collision, the collision must have happened once the star had formed," said Bill Chaplin, astrophysicist at the University of Birmingham and lead author, in a press release. "That is how we have been able to use the asteroseismically-determined age to place new limits on when the Gaia-Enceladus event occurred."
The team suggest v Indi must have been in place before the Milky Way ate up Gaia-Enceladus and used its age and mass measurements to hypothesize the galactic cannibalism must have begun somewhere between 11.6 and 13.2 billion years ago. However, the researchers note the new age relies on some assumptions being made about Gaia-Enceladus and its collision.
The ancient history of our home galaxy is an area of intense research and astronomers are trying to piece together how the Milky Way came to be in the warped and twisted spiral shape we see today. Piecing together its formation and how galactic mergers may have contributed will help us better understand just how galaxies come to be -- and the implications that might have for life and the universe, as a whole.
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