A Disturbance In The Force: "Galactic Archaeologists" Find Ancient Spiral Patterns Embedded In The Milky Way Galaxy

Thursday, 20 September 2018 - 1:11PM
Astronomy
Space
Thursday, 20 September 2018 - 1:11PM
A Disturbance In The Force: "Galactic Archaeologists" Find Ancient Spiral Patterns Embedded In The Milky Way Galaxy
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Composite: NASA, ESA, and Z. Levay (STScI/AURA)/Outer Places
Last April the ESA Gaia satellite released its first big dump of data, which gave astronomers the brightness, distances, and positions of roughly 1.7 billion stars in the Milky Way galaxy. Now, months later, that data is already being used to make breakthroughs in the burgeoning field of "galactic archaeology": according to research by the Institute of Cosmos Sciences of the University of Barcelona, the Milky Way had a close call with the Sagittarius Dwarf galaxy hundreds of millions of years ago, which left lasting patterns in our galaxy's arrangement of stars.

Everyone knows that the Milky Way itself has a spiral shape, but it turns out that the gravitational disturbances caused by Sagittarius actually made smaller spirals within our galaxy 300 and 900 million years ago – some of which can still be spotted. According to Teresa Antoja, one of the researchers associated with the new study: "The study implies, definitely, that our galaxy's disk is dynamically young, sensitive to disturbances and changing over time. 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."



The discovery of these spiral sub-structures within the Milky Way is all thanks to Gaia, which offers astronomers a previously unheard-of amount of data to explore. "I've been working on trying to understand the Milky Way and the formation of the Milky Way for a large fraction of my scientific career," said astrophysicist David Hogg, "and the amount of information this is revealing in some sense is thousands or even hundreds of thousands of times larger than any amount of information we've had previously."

This new discovery marks the first of many potential breakthroughs in our understanding of the Milky Way's history, as well as the dawn of a new, exciting time for astronomy.
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