Our Milky Way galaxy is known to have more than 50 satellite galaxies. The peer-reviewed Astrophysical Journal published their results on February 17. … An important step towards a more complete reconstruction of our galaxy’s billion-year history. These astronomers said of their study of stellar streams in the Milky Way that their new results are: Where earlier studies had reconstructed such mergers ‘by hand,’ the new study applied a systematic statistical evaluation of 257 stellar streams, globular clusters and satellite galaxies … He and his team said their new work constitutes an “atlas” of mergers with our home galaxy, the Milky Way. Khyati Malhan of the Max Planck Institute for Astronomy in Heidelberg, Germany, led the new work. There was also a possible seventh merger in the data. Each group is a merger taking place with the Milky Way. Plotting them according to their energy and momentum revealed that 25% of these objects fall into six distinct groups. In total they studied 170 globular clusters, 41 stellar streams and 46 satellites of the Milky Way. They said their new study has revealed a history of Milky Way mergers. Early this morning (February 17, 2022), astronomers announced a new insight obtained via Gaia. Because, after all, if a star is moving on a particular path now, it’s likely been on that same path for millions or billions of years. And it’s about how that knowledge has enabled astronomers to deduce a history of star motions in our galaxy. It’s about astronomers analyzing Gaia data to learn about star motions.
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So – as they analyze Gaia’s data – astronomers are coming to know how Milky Way stars are moving over time. But, in recent years, ESA’s mighty Gaia satellite has acquired astrometric measurements for more than a billion Milky Way stars. And, over time, they get a sense of how stars are moving across our sky, and therefore in our Milky Way galaxy. Astronomers measure a star position, then measure it again. History of Milky Way mergersĪstrometry is the branch of astronomy that deals with precise measurements of star positions. The dots and squares in purple are objects brought into the Milky Way by the newly identified Pontus merging galaxy. The squares represent the location of globular clusters, the triangles the location of satellite galaxies, and the small dots are stellar streams. Artist’s concept of the Milky Way, as revealed by Gaia satellite data.