Galaxies: Merger with consequences
Galaxy NGC 7727 in the constellation Aquarius shows a strange shape: what is behind it?
The irregular galaxy NGC 7727 in the constellation Aquarius resembles cosmic cotton candy. The strange structure arose from the merger of two world islands.
Galaxy NGC 7727 is located about 90 million light-years away from us in the constellation Aquarius, and was recently observed in detail by the eight-meter-diameter Gemini Southern Telescope. It does not exhibit a classic spiral or disk structure, but is one of the world’s irregular or special islands, or strange galaxies.
NGC 7727 emerged from the merger of two small islands in the world and is still in the process of forming a new structure. During the collision, the two original disks of stars and the accumulations of gas and dust were intensely mixed. Long filaments of stars formed around the center of the galaxy, and clumps of gas and dust were stimulated to form stars en masse. They appear as clusters of bright, bluish stars in filaments. In the long term, NGC 7727 will likely evolve into an elliptical galaxy, that is, an elliptical disk without spiral arms.
At the center of NGC 7727, the merger has not yet been completed because the two supermassive black holes from previous galaxies are still present and orbiting their common center of gravity at a distance of 1,600 light-years. The larger of the two has 154 million solar masses, and the second, much less massive, still has 6.3 million solar masses (for comparison: the central black hole in the Milky Way system has 4.3 million solar masses). The two black holes will likely combine to form a more massive structure in about 250 million years. The two black holes, or their immediate surroundings, appear as bright spots in the yellow central region of NGC 7727.
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