Why do stars near the center of the Milky Way move so fast?
Quick Answer
They orbit a huge concentration of mass, including the supermassive black hole Sagittarius A*. The closer a star is to the center, the faster gravity makes it move.
The Full Story
The center of the Milky Way contains a very dense region of stars, gas, and dark matter, plus a supermassive black hole called Sagittarius A*. Observations of stars such as S2 showed that some orbit the central black hole in only about 16 years, reaching speeds of thousands of kilometers per second near periapsis. Those fast motions are a direct sign of intense gravity in a compact region. The work helped confirm the existence of a black hole with a mass of about 4 million Suns. This was one of the strongest pieces of evidence for a supermassive black hole in our galaxy.
Key Facts
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"Why are stars racing around the Milky Way’s black hole?"
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