Gaia Detects Disturbance In Milky Way

Posted: Sep 22 2018, 1:13pm CDT | by , in Latest Science News


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Gaia Detects Disturbance in Milky Way
Credit: ESA

New study suggests that our Milky Way galaxy is still experiencing the effects of a near collision that occurred sometime in the past 300-900 million years.

Using data from Europe’s Gaia satellite, researchers have discovered many unusual substructures in the Milky Way galaxy. The analysis suggests that these substructures were likely caused by a near-collision between Milky Way and a dwarf galaxy, Sagittarius. The structures remained hidden until Gaia brought them to light.

“We have observed shapes with different morphologies, such as a spiral similar to a snail's shell. The existence of these substructures has been observed for the first time thanks to the unprecedented precision of the data brought by Gaia satellite, from the European Space Agency (ESA),” said Teresa Antoja, who works as research fellow on the Gaia Mission. “These substructures allow us to conclude that the disk of our galaxy suffered an important gravitational disturbance about 300 and 900 million years ago.”

When the small galaxy passed near the Milky Way, it gravitationally disturbed millions of stars. The phenomena influenced the motion of almost six millions of stars in our galaxy’s disk and left them moving like ripples on a pond.

"It is a bit like throwing a stone in a pond, which displaces the water as ripples and waves," said Antoja.

“One of the most distinguishable forms we saw is the spiral pattern of the stars near the sun, which had never been seen before. Actually, the observed shapes in the graphics were so clear (unlike common cases) that we thought it could be a mistake in the data.”

Researchers performed many tests on the data to look for errors but the results remained consistent and never changed. Accepting this leads to only one logical conclusion: the substructures do indeed exist in the Milky Way. The presence of these features also implies that our galaxy's disk is dynamically young and continues to change over time.

“We know our galaxy is 'cannibal,' and has grown while eating other small galaxies, like it is doing now with the Sagittarius dwarf galaxy." Amina Helmi, researcher at the University of Groningen, said.

The discovery was made possible by European Space Agency’s Gaia satellite. Launched in 2013, Gaia not only accurately measures the positions of stars but also provide accurate information on their movements on the plane of the sky.

“This is exactly the kind of discovery we hoped would come from the Gaia data,” said Timo Prusti, Gaia project scientist at ESA. “The Milky Way has a rich history to tell, and we are starting to read that story.”

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.




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