S2 Star Hits 7,650 km/s Around Sagittarius A*, Confirming 4.3 Million-Solar-Mass Black Hole
Updated
Updated · spacedaily.com · Jul 25
S2 Star Hits 7,650 km/s Around Sagittarius A*, Confirming 4.3 Million-Solar-Mass Black Hole
1 articles · Updated · spacedaily.com · Jul 25
Summary
S2 reaches about 7,650 km/s—roughly 2.55% of light speed—at its closest pass around Sagittarius A*, giving astronomers a rare direct probe of extreme gravity at the Milky Way’s center.
Its just-under-16-year, highly elongated orbit shows that about 4.3 million solar masses are packed inside a region smaller than S2’s roughly 120-AU pericentre, ruling out any stable cluster of dark remnants.
Observations around S2’s 2018 pericentre detected the relativistic redshift expected from Einstein’s theory, and a 2020 analysis found Schwarzschild precession of about 12 arcminutes per orbit.
Nearly 30 years of infrared tracking by teams led by Reinhard Genzel and Andrea Ghez—using adaptive optics and ESO’s GRAVITY instrument—turned a dust-hidden blur into precise stellar orbits and underpinned their 2020 Nobel Prize.
The orbit-based evidence was later complemented, not replaced, by the Event Horizon Telescope’s 2022 image of Sagittarius A*, linking stellar motions far out to the black hole’s immediate surroundings.
Could the relentless, high-speed dance of star S2 eventually expose a hidden flaw in Einstein's legendary theory of gravity?
Beyond the invisible shadow, what mysterious exotic matter could possibly mimic the gravitational pull of millions of suns?
If our galaxy's central black hole is seemingly quiet, what unseen forces are triggering its sudden, violent expulsions of hot gas?
Testing General Relativity and Dark Matter at the Galactic Center: Precision Tracking of S2’s Orbit Around Sagittarius A*
Overview
This report explores how astronomers have tracked the star S2’s orbit around the supermassive black hole Sagittarius A* for decades, using advanced instruments like the VLT’s NACO and the GRAVITY interferometer. By precisely measuring S2’s motion, especially during its 2018 close approach, scientists confirmed Einstein’s General Relativity in a strong gravitational field and detected relativistic effects. These observations also set strict limits on dark matter near the black hole and revealed mysteries about star and planet survival in the Galactic Center. The findings help explain how black holes and galaxies grow together, shaping our understanding of the universe.