17-05-2025
Star 20 times the Sun's mass caught gorging on gas in cosmic birth ritual
Astronomers have captured a stellar feast in action — the clearest view yet of a massive baby star devouring gas to fuel its rapid growth.
The star, dubbed HW2, lies about 2,300 light-years from Earth in a stellar star-forming region known as Cepheus A.
Weighing in at 10 to 20 times the mass of our sun, HW2 is a rare example of a massive protostar caught in the act of formation.
The discovery also offers new insight into a fundamental astrophysical mystery: how massive stars, which often end their lives in spectacular supernova explosions, manage to gather such enormous amounts of mass during their formation.
Using radio observations of ammonia, a molecule common in interstellar space and a common cleaning agent used on earth, astronomers were able to map the swirling disk of gas feeding the star, despite thick clouds of dust cloaking the region, making it obscure.
The observations confirm that even the universe's most massive stars grow by pulling in gas from surrounding disks, following the same fundamental process as their smaller stellar siblings.
"We are always trying to get general rules that can explain the largest number of phenomena we observe," study leader Alberto Sanna, a researcher at the National Institute for Astrophysics in Italy, said in a release.
"Our findings strongly support that the same physical processes, although scaled up, can form both stars like our sun as well as stars of tens of solar masses."
In 2019, the team used the Very Large Array radio telescope network in New Mexico to track the radio glow of ammonia molecules, which glow brightly at radio wavelengths. This allowed them to pierce through the dense dust cocoon that blocks visible light to get a look as close as possible to the star.
The data show that gas in HW2's accretion disk is plunging inward at a staggering pace, fueling the young star at a rate of about two Jupiter masses per year — one of the fastest stellar growth rates ever recorded. But HW2's future depends heavily on its surroundings, Sanna noted.
The team also found an uneven distribution of gas in the disk. According to their observation, the eastern side of the disk holds nearly twice as much material as the western side and displays more turbulence.
This imbalance hints that the disk may be receiving an external boost, possibly from a nearby filament-like stream of gas and dust acting as a cosmic pipeline.
Such streamers are increasingly believed to connect forming stars with their outer envelopes, channeling fresh material to keep growth going.
While these structures around HW2 remain unseen for now, the study lays out predictions that future telescopes can test, Sanna said.
"We need to understand for how long HW2 can keep growing," he added.
The results of the study will soon be published in the journal Astronomy & Astrophysics. It is available on the arXiv preprint server.
