Astronomers spot the closest, fastest star ever seen orbiting our galaxy's monster black hole

Key Points:

• Astronomers have discovered S301, the closest and fastest star known to orbit the Milky Way's central black hole, Sagittarius A*, completing an orbit every 8.7 years at about 8% the speed of light.
• S301's orbit is much tighter than the previously studied star S2, passing roughly 12 astronomical units from the black hole, enabling potential measurements of the black hole's spin within the next decade.
• The star's highly elongated orbit suggests it originated from a disrupted binary system, and its motion already exhibits strong general relativistic effects such as Schwarzschild precession.
• Detecting S301 required advanced imaging techniques and upgrades to the GRAVITY instrument due to its extreme faintness and crowded stellar environment near the black hole.
• Continued observations, including measuring the star's radial velocity, aim to resolve orbital ambiguities and could confirm the black hole's rotation, providing stringent tests of Einstein's general relativity and alternative gravity theories.