How did adaptive optics improve observations of the galactic centre?

Adaptive optics is a technology that improves the resolution of ground-based telescopes by rapidly adjusting the shape of the mirror to compensate for atmospheric turbulence, which otherwise blurs astronomical images.1

In the context of the Milky Way Galaxy, this technology was instrumental in allowing astronomers to overcome the limitations of Earth's atmosphere to study the galactic centre in high detail. By using adaptive optics, researchers—most notably Reinhard Genzel and Andrea Ghez—were able to achieve the resolution necessary to identify and track the individual orbits of stars near the centre of the galaxy.23

These precise orbital measurements revealed that these stars were circling a compact, massive object rather than an extended stellar cluster. This evidence confirmed that the radio source Sagittarius A* is a supermassive black hole with a mass approximately four million times that of the Sun, a discovery that earned Genzel and Ghez the 2020 Nobel Prize for Physics.23