For the first time, astronomers have identified the birthplace of an energetic jet emitted by a young star, utilizing the Atacama Large Millimeter/submillimeter Array (ALMA) located in Chile. This groundbreaking discovery centers on HH 211, an infant star producing immense energy jets, situated 1,000 light-years from Earth in the constellation Perseus.
On September 17, 2025, the findings were shared with the scientific community. The star formation process, while seemingly straightforward, remains one of the universe”s enduring mysteries. Typically, stars develop in dense clouds composed of cold gas and dust. Once these clouds attain a critical mass, they collapse under their gravitational force, resulting in the formation of a protostar.
As these nascent stars evolve, they draw in material from their surroundings, forming a rotating disk of gas and dust, known as an accretion disk. This material gradually coalesces and falls into the star, facilitating its growth. However, if the accretion disk rotates too quickly, the material struggles to descend toward the star. To counteract this, astronomers theorize that young stars expel some of this material in the form of energetic jets, referred to as protostellar jets, which may assist in the inward movement of material.
Understanding these jets has posed significant challenges for astronomers, as they originate from regions very close to the star, rendering them invisible, even to powerful telescopes. Consequently, the mechanisms of their ejection and their precise origins have remained elusive. Past research has suggested that the magnetic fields within protostellar systems might play a crucial role in propelling these jets.
A study published on August 13 in the journal Scientific Reports utilized ALMA to investigate HH 211, a Herbig-Haro object characterized by bright nebulosity produced by the powerful outflows of newborn stars. At just 35,000 years old, this protostellar system contains a central star that is only 0.06 times the mass of the sun.
HH 211 features a striking bipolar jet, with two beams of ionized material expelled in opposite directions. Remarkably, this system represents one of the few known instances in which a magnetic field has been detected, providing a unique opportunity to explore magnetic field-driven jet ejection models.
The observations from ALMA revealed that the jet is traveling at approximately 66 miles per second (107 kilometers per second) but rotates at a slower pace, indicating a specific angular momentum. This observation suggests that the bipolar jet is effectively removing excess rotational energy from the accretion disk.
By applying principles of angular momentum and energy conservation, researchers determined that the jet originates from the innermost edge of the accretion disk, located about 0.02 astronomical units, or nearly 1.85 million miles (3 million kilometers), from the protostar. These findings support models that propose magnetic fields can act as a slingshot to propel gas outward.
The stunning image produced by the James Webb Space Telescope (JWST) captures the colorful display of the bipolar jet in near-infrared wavelengths. However, the dense dust surrounding the central region obscures JWST”s view, which is significant as this area is where the jet originates. The new study utilizing ALMA data has exposed the critical thin section at the center in submillimeter wavelengths, allowing for a comprehensive understanding of star formation.
The grayscale image produced by ALMA distinctly shows the jet being ejected from the accretion disk, marking the first time the launch site of a protostellar jet has been documented. This discovery reinforces the idea that these jets are vital for the growth of young stars by facilitating the release of angular momentum from the accretion disk, thus allowing material to more easily fall onto the star.
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