At the center of a cosmic dust cloud, astronomers detected an invisible star. It's wrapped in a rotating gas disk. This disk works like a set of scales: the gas speed at different distances from the center reveals the star’s mass.

Observing in the radio range, scientists peered through cosmic dust and measured gas velocities using spectroscopy — breaking light into colors. They found carbon monoxide (carbon) and sulfur in the disk. The outer regions spin slowly, just a kilometer or two per second, while closer to the star, the gas races tens of times faster. This gradient, like the needle of a scale, pointed to the exact mass.