Weighing a Stellar Giant Baby express

Original: "Unveiling the First O-Type Bloated Star Candidate through ALMA and EVLA Observations"
arXiv:2601.12336 · 2026-01-18 · CC BY 4.0 · 1 min
Astronomers calculated the mass of a young giant star by measuring gas velocities in its rotating disk.

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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.

The pattern is simple: the closer to the center, the faster the motion. It was discovered by Kepler while observing planets. The same principle allowed us to weigh the star.

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.

Right now the star weighs 10–15 solar masses. It's still packing on weight. When the fuel runs out, it will go supernova — an explosion that could outshine an entire galaxy.

The star is only a few tens of thousands of years old, a blink in cosmic time, yet it already weighs as much as 15 Suns. For comparison, our Sun is 4.5 billion years old and is only halfway through its life.

Scientists
Subrahmanyan ChandrasekharDavid CharbonneauIsaac NewtonJohannes KeplerWilliam BoruckiHendrik Lorentz
Concepts
alma vla hot gas spiral galaxy