PARIS — The Gaia space probe on Monday
unveiled its latest discoveries in its quest to map the Milky Way in
unprecedented detail, surveying nearly two million stars and revealing
mysterious “starquakes” which sweep across the fiery giants like vast tsunamis.
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The mission’s third data set, which was released to
eagerly waiting astronomers around the world at 10am GMT, “revolutionizes our
understanding of the galaxy,” the
European Space Agency (ESA) said.
ESA Director-General Josef Aschbacher told a press
conference that it was “a fantastic day for astronomy” because the data “will
open the floodgates for new science, for new findings of our universe, of our
Milky Way”.
Some of the map’s new insights came close to home,
such as a catalogue of more than 156,000 asteroids in our Solar System “whose
orbits the instrument has calculated with incomparable precision,” Francois
Mignard, a member of the Gaia team, told AFP.
But Gaia also sees beyond the
Milky Way, spotting
2.9 million other galaxies as well as 1.9 million quasars — the stunningly
bright hearts of galaxies powered by supermassive black holes.
The Gaia
spacecraft is nestled in a strategically positioned orbit 1.5 million
kilometers from Earth, where it has been watching the skies since it was
launched by the ESA in 2013.
The observation of starquakes, massive vibrations
that change the shape of the distant stars, was “one of the most surprising
discoveries coming out of the new data”, the ESA said.
Gaia was not built to observe starquakes but still
detected the strange phenomenon on thousands of stars, including some that
should not have any — at least according to our current understanding of the
universe.
‘Turbulent’ galaxy
“We have a fantastic new
gold mine to do the asteroseismology of hundreds of thousands of stars in our
Milky War galaxy,” said Gaia team member Conny Aerts.
Gaia has surveyed more than 1.8 billion stars but
that only represents around one percent of the stars in the Milky Way, which is
about 100,000 light years across.
The probe is equipped with two telescopes as well as
a billion-pixel camera, which captures images sharp enough to gauge the
diameter of a single strand of human hair 1,000km away.
It also has a range of other instruments that allow
it to not just map the stars, but measure their movements, chemical
compositions and ages.
The incredibly precise data “allows us to look more
than 10 billion years into the past history of our own Milky Way,” said Anthony
Brown, the chair of the Data Processing and Analysis Consortium which sifted
through the massive amount of data.
The results from Gaia are already “far beyond what
we expected” at this point, Mignard said.
They show that our galaxy is not moving smoothly
through the universe as had been thought but is instead “turbulent” and
“restless”, he said.
“It has had a lot
of accidents in its life and still has them” as it interacts with other
galaxies, he added. “Perhaps it will never be in a stationary state.”
“Our galaxy is indeed a living entity, where objects
are born, where they die,” Aerts said.
‘Tens of thousands of exoplanets’
“The surrounding galaxies
are continuously interacting with our galaxy and sometimes also falling inside
it”.
Around 50 scientific papers were published alongside
the new data, with many more expected in the coming years.
Gaia’s observations have fuelled thousands of
studies since its first dataset was released in 2016.
The second dataset in 2018 allowed astronomers to
show that the Milky Way merged with another galaxy in a violent collision
around 10 billion years ago.
It took the team five years to deliver the latest
data, which was observed from 2014 to 2017.
The final dataset will be released in 2030, after
Gaia finishes its mission surveying the skies in 2025.
Monday’s release confirmed only two new exoplanets —
and 200 other potential candidates — but far more are expected in the future.
“In principle Gaia, especially when it goes on for
the full 10 years, should be capable of detecting tens of thousands of
exoplanets down to Jupiter’s mass,” Brown said.
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