Figure 4. Rotation curve of a typical spiral galaxy: predicted (A) and observed (B). Dark matter can explain the 'flat' appearance of the velocity curve out to a large radius. Dark matter – Wikipedia

From

From the Contraction of Celestial Bodies to Their Shortest Rotation Period until the Heating of the Stars and the Universe Global Theory

José Luís Pereira Rebelo Fernandes

International Journal of Physics. 2021, 9(2), 96-113 doi:10.12691/ijp-9-2-5