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Clues left at a galactic hit-and-run

Unusual gas ripples offer signs of a dwarf galaxy speeding away

By
3:55pm, January 12, 2016

GALACTOSEISMIC ACTIVITY  The Milky Way’s gas (left image) and stars (right) might have been disturbed by a close run-in with a dwarf galaxy (blob at bottom left of both images), as seen in this computer simulation.

Galactoseismology
\guh-LAC-toe-saiz-MAHL-ah-jee\  n.

The study of disturbances in a galaxy’s structure (essentially, galaxy quakes) to discover dark, but massive, cosmic objects.

KISSIMMEE, Fla. — Ripples in the Milky Way’s outer layers of gas were the first clue. Now, scientists suspect they have found a small, faint galaxy that brushed past our galaxy a few hundred million years ago. This dwarf galaxy doesn’t have many stars, but it is rich in dark matter, the invisible but predominant source of mass in the universe. Sukanya Chakrabarti, an astronomer at the Rochester Institute of Technology in New York, reported the findings January 8 at a meeting of the American Astronomical Society.

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