ESO’s VLTI images of stars at the center of the Milky Way

These annotated images, obtained with the GRAVITY instrument on ESO’s Very Large Telescope Interferometer (VLTI) between March and July 2021, show stars orbiting very close to Sagittarius A*, the supermassive black hole at the heart of the Milky Way. One of these stars, named S29, was observed as it was making its closest approach to the black hole at 13 billion kilometers, just 90 times the distance between the Sun and Earth. Another star, named S300, was detected for the first time in new VLTI observations reported by ESO.

Using Gemini North of the international Gemini Observatory, a Program of NSF’s NOIRLab and ESO’s VLT, astronomers have measured more precisely than ever before the position and velocity of these stars S29 and S55 (as well as stars S2 and S38), and found them to be moving in a way that shows that the mass in the center of the Milky Way is almost entirely due to the Sagittarius A* black hole, leaving very little room for anything else.