This Star Holds the Key to New Research Unlocking Exact Date the Milky Way Devoured Dwarf Galaxy Gaia-Enceladus

Monday, 13 January 2020 - 5:02PM
Space
Astronomy
Monday, 13 January 2020 - 5:02PM
This Star Holds the Key to New Research Unlocking Exact Date the Milky Way Devoured Dwarf Galaxy Gaia-Enceladus
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Credit: NASA, ESA, S. Beckwith (STScI) and the Hubble Heritage Team (STScI/AURA)
Over 10 billion years ago, the Milky Way galaxy devoured a smaller dwarf galaxy named Gaia-Enceladus. We can see the wreckage in the skies, but we have never been able to establish when exactly these two galaxies collided with each other.


Until now: An international team of over 80 scientists led by researchers at the University of Birmingham has been studying one single star because they believe it holds the key to definitively unlocking when this galactic crash happened, according to a report from CNET.


Using data from the NASA Transiting Exoplanet Survey Satellite, or TESS, "We have been able to use the asteroseismically-determined age to place new limits on when the Gaia-Enceladus event occurred," said Bill Chaplin, lead author of the study and an astrophysicist at the University of Birmingham.


Asteroseismology is the practice of studying stars by observing their oscillations – which give off certain frequencies. By interpreting these frequencies, astronomers can then deduce things like its chemical composition or relative age.


The star – v Indi, in the constellation Indus – is about 95 light-years away and can be seen with the naked eye. Based on the new information we have about v Indi, scientists now estimate it to be approximately 11 billion years old.


Crucially, it sits in a part of the Milky Way galaxy that we know was fundamentally changed by the impact. "Since the motion of ν Indi was affected by the Gaia-Enceladus collision, the collision must have happened once the star had formed," Chaplin explained.


Instead of dating the crash to 10 billion years ago, we now have better information that places the crash anywhere between 11.6 to 13.2 billion years ago. Admittedly, when you're dealing with scales in the billions, get "one billion years closer" to accuracy doesn't feel like the greatest discovery ever – but it's important to keep in mind that we have only just begun to accurately understand the cosmos.


These seemingly minute discoveries will pave the way for deeper understanding to become second nature to the human race so that, instead of navigating by traffic lights, one day we may navigate by the stars. Any step in that direction, no matter how seemingly trivial, is progress in its own way.


"Because we see so many stars from Gaia-Enceladus, we think it must have had a large impact on the evolution of our Galaxy. Understanding that is now a very hot topic in astronomy, and this study is an important step in understanding when this collision occurred," concluded the study's co-author, Dr. Ted Mackereth, a galactic archaeology research fellow at the University.


A paper has just been published in the journal Nature Astronomy.
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