Astronomers Find Shell Structures in Milky Way Galaxy for First Time

A team of astronomers from Rensselaer Polytechnic Institute, the University of Pennsylvania, Flatiron Institute, and Queen’s University has spotted two shells in the Virgo Overdensity region and two shells in the Hercules Aquila Cloud region of the Milky Way.

These structures were produced about 3 billion years ago, when a dwarf galaxy plunged into the Milky Way’s center and was ripped apart by the gravitational forces.

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Image credit: Rensselaer Polytechnic Institute.

Stars identified by Donlon II et al. have formed shell structures in the aftermath of a radial merger occurring 3 billion years ago

About two decades ago, astronomers identified an unusually high density of stars called the Virgo Overdensity.

Star surveys revealed that some of these stars are moving toward us while others are moving away, which is also unusual, as a cluster of stars would typically travel in concert.

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This video shows an N-body simulation of a dwarf galaxy crashing through the center of the Milky Way galaxy.

This smaller galaxy is ripped apart and its stars are flung into the halo of the Milky Way, creating shell structure.

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