Mystery Cloud at Milky Way’s Center May Hold Clues to Star Birth
Near the crowded center of a mysteriously dense galactic cloud, where billowing clouds of gas and dust cloak a supermassive black hole three million times as massive as the sun — a black hole whose gravity is strong enough to grip stars that are whipping around it at thousands of kilometers per second — one particular cloud has baffled astronomers. Indeed, the cloud, dubbed G0.253+0.016, defies the rules of star formation. In infrared images of the galactic center, the cloud — which is 30 light-years long — appears as a bean-shaped silhouette against a bright backdrop of dust and gas glowing in infrared light. The cloud’s darkness means it is dense enough to block light.
According to conventional wisdom, clouds of gas that are this dense should clump up to create pockets of even denser material that collapse due to their own gravity and eventually form stars. One such gaseous region famed for its prodigious star formation is the Orion Nebula. And yet, although the galactic-center cloud is 25 times denser than Orion, only a few stars are being born there — and even then, they are small. In fact, the Caltech astronomers say, its star-formation rate is 45 times lower than what astronomers might expect from such a dense cloud.