Astronomers using the ALMA telescope have identified a young stellar system containing nine stars in the early stages of formation within the NGC 6334-43 hot core. According to a study published on arXiv, these stars are gravitationally bound and connected by a 24,700 AU gas filament, providing new data to study how multiple-star systems evolve.
How did astronomers find the nine-star system?
Researchers identified the system while examining the chemistry of complex organic molecules around hot cores. Using data from the CoCCoA survey and the ALMA telescope, the team analyzed 25 different hot cores. One specific area, NGC 6334-43, sits over 4,300 light-years away from Earth.
While analyzing high-resolution emissions of dust and gas, the team spotted nine compact sources located close to one another. These sources are connected by a single gas filament measuring 24,700 AU in length. To ensure these stars weren’t just randomly scattered, researchers performed a stability check. By comparing gravitational and kinetic energy, they confirmed the nine sources belong to a single, gravitationally bound system.
The gas filament connecting these nine stars is approximately 24,700 AU long. For perspective, one Astronomical Unit (AU) is the average distance between the Earth and the Sun.
What distinguishes the ALMA2 and ALMA6 subgroups?
The study found that the nine-star system isn’t uniform. Instead, it contains two distinct subgroups that show different evolutionary signatures. This variety helps scientists understand how different parts of a single system can age at different rates.
The ALMA2 subgroup is a triple system. It consists of a close hot-core pair labeled ALMA2a/b and a younger component, ALMA2c. Researchers found no evidence of a shared disk between these three, a finding they say is consistent with core fragmentation. In contrast, the ALMA6 subgroup is a binary system characterized by an unusually long, spiral-arm-like structure. The components in ALMA6 are spaced 1,530 AU apart. While ALMA6a is more evolved, ALMA6b remains in the pre-stellar stage.
Other sources within the larger system show even more diversity. Some stars are already driving active outflows, which is a primary signature of newborn stars. This mix of stages suggests that star formation within a single system is a staggered process rather than a single, simultaneous event.
How does this discovery affect star formation theories?
The existence of this nine-member system provides a testing ground for three primary theories of star formation: disk fragmentation, core fragmentation, and filament fragmentation. Because this system is far from massive stars, testing these theories is traditionally difficult.
Filament fragmentation occurs when a long, threadlike cloud of gas breaks into clumps along its length. Usually, this process limits the age gap between sibling stars to about 500,000 years. Because the nine stars in NGC 6334-43 show a wide range of ages, some researchers might assume they didn’t form from a single filament.
However, the researchers propose a different outlook. They noted that the age spread seen in filament fragmentation is comparable to the time required to form a single massive star. Since the stars in this system are not yet fully grown, the study concludes that a filament-fragmentation origin remains a feasible explanation for the nine-member system.
Frequently Asked Questions
What is NGC 6334-43?
NGC 6334-43 is a “hot core” located approximately 4,300 light-years away, which serves as a site for active star formation.
What is the ALMA telescope?
The Atacama Large Millimeter/submillimeter Array (ALMA) is a high-resolution radio telescope used to observe dust and gas emissions in space.
What is core fragmentation?
Core fragmentation is a process where a single dense core of gas breaks into multiple pieces, eventually forming multiple stars or binary systems.
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