In a satellite galaxy of the Milky Way, astronomers have spotted a star similar to the old stars in the galactic halo. The discovery supports the theory that our galaxy grew by absorbing small satellite.
According to the model of galaxy formation hierarchical said, the current large galaxies grew by swallowing smaller neighbors. The Milky Way would be formed in part of small satellite galaxies absorbed during its history. But the apparent absence in the current satellite galaxies, stars chemically similar to the oldest of the Milky Way had cast doubt on this scenario. Spectroscopic analysis of an old star in the Sculptor dwarf galaxy by the team of Anna Frebel, the Harvard-Smithsonian Center for Astrophysics, raises the question today: its chemical composition is similar to that of stars the galactic halo, in agreement with the scenario based on the hierarchical model.
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