Gas Streamers May Explain Giant Star Formation

• New observations suggest massive stars grow via vast gas streamers, challenging long-held theories about disk-fed stellar development.

Rethinking How Massive Stars Grow

Massive stars, those exceeding eight times the Sun’s mass, form rapidly despite emitting intense radiation and stellar winds. These forces should theoretically blow away the gas needed for further growth, yet observations show they continue to accumulate mass. Traditionally, astronomers believed rotating disks of gas surrounding young stars acted as feeding mechanisms. However, recent findings suggest a different process may be at play.

A research team from Kyoto University and the University of Tokyo has identified vast gas streamers delivering material directly to young giant stars. These structures span thousands of astronomical units, functioning like interstellar highways that bypass the need for conventional disks. Using the ALMA telescope in Chile, which observes millimeter wavelengths, the team captured high-resolution images of these distant stellar nurseries. The data revealed spiraling gas flows rather than the expected symmetrical disks.

Streamers Instead of Disks

Instead of a large rotating disk, the researchers observed twisting streamers funneling gas toward the star’s center. These streamers resemble giant straws, channeling material from remote regions straight into the star’s core. One particular streamer displayed signs of both rotation and inward motion, indicating it was actively feeding the star. This behavior contradicts the assumption that stellar feedback—winds and radiation—would halt further accretion.

The presence of such streamers creates a dense environment around the star, akin to a traffic jam of gas and dust. This congestion allows the star to continue growing despite its own disruptive emissions. Lead researcher Olguin noted that what was initially thought to be a disk turned out to be either absent or significantly smaller than expected. These findings suggest that streamers alone may be sufficient to sustain the growth of massive stars.

Expanding the Search for Stellar Fueling Mechanisms

The team is now investigating whether streamer-fed growth is a widespread phenomenon across other star-forming regions. By examining additional sites, they aim to determine if this mechanism is common or unique to specific environments. Researchers are also focusing on the innermost regions around stars to detect any hidden, compact disks. Discovering such structures could refine existing models of stellar formation.

If no disks are found, the role of streamers may need to be reconsidered as a primary driver of mass accumulation. This shift could influence how astronomers understand the lifecycle of massive stars and the dynamics of early stellar environments. The study opens new questions about the balance between gravitational infall and radiative feedback. Future observations will be critical in confirming whether streamers are a universal feature of high-mass star formation.