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'I'm really excited about the results of the Nature paper. Using chemical abundances, we chemically tagged stars in two groups of stars in the Milky Way, our home galaxy, to figure out if they formed in the Milky Way or in a small galaxy that the Milky Way accreted, which just means that the Milky Way pulled it in. This is just like DNA testing allows us to see how two people are related to each other.
My main contribution to this work was selecting stars for the initial observations. We found that stars in two of these groups, called Tri-And and A13, not only have nearly identical abundances to each other across several elements, but have similar abundances to the Milky Way's disc. We ran computer simulations and found that an accreted galaxy can dynamically perturb the disk, and literally, so come through, perturb the disc, and literally set the disc oscillating. And this can explain how these groups of stars were relocated or galactically evicted to the outer realms of the disc.
Ultimately, this work helps us understand how complex the disk really is, and how common these groups are at the fringe of the disk. And for future work, we're interested in carrying out similar analysis for other groups of stars in the Milky Way to see how common kicked out disk stars are. Stay tuned!' -- says Dr. Allyson Sheffield, associate professor of physics, LaGuardia Community College, part of The City University of New York (CUNY)