Hubble Telescope Records Unprecedented Stellar Jet from Protostar IRAS 18162-2048

In January 2026, the Hubble Space Telescope provided astronomers with exceptionally high-resolution data regarding the phenomenon of extreme star formation. The focal point of this study was a massive eruption originating from the protostar IRAS 18162-2048, which stands as the most massive entity within the L291 molecular cloud. This stellar nursery is located approximately 5,500 light-years away from our solar system, situated in the constellation of Sagittarius.

The recorded gas emission, or stellar jet, has set a new speed record among all observed protostellar outflows. Individual fragments of this cosmic stream reach velocities exceeding 1,000 kilometers per second, which is equivalent to approximately 3.5 million kilometers per hour. Additionally, this jet has been recognized as the longest ever documented, extending across 32 light-years—a distance that is eight to ten times the diameter of our solar system. While such polar flows, ejected along the axis of rotation, are common in many stellar systems, the sheer scale of this particular discharge makes IRAS 18162-2048 an extraordinary case.

With a mass estimated at roughly 20 times that of the Sun, the protostar IRAS 18162-2048 serves as a prime example of a massive young star whose development differs significantly from its less massive counterparts. Its total luminosity is immense, calculated at approximately 17,000 solar luminosities. In the images captured by Hubble, the Herbig-Haro (HH) 80 and HH 81 objects are clearly visible, glowing brilliantly in shades of green and pink. These luminous structures are formed by the high-speed collision of gas from the jet with previously expelled material, generating shock waves that heat the surrounding interstellar clouds.

The HH 80 and HH 81 objects are notable for being among the brightest known formations of this type, powered by a massive young star rather than the more common HH objects associated with low-mass stars. The energetic activity of the protostar is driven by intense magnetic fields that redirect a portion of the material from the surrounding accretion disk toward the star's polar regions. In 2010, it was established that the HH 80–81 jet emits polarized radio waves, providing the first evidence of a magnetized jet in a protostar, with the magnetic field strength estimated at 20 nT.

Spectral observations, including those from Hubble, have allowed for the measurement of the jets' proper motions, which complements the radial velocity data obtained through spectroscopy. The collection of images taken in 1995, 2018, and 2026 enables scientists to track structural changes and the kinematics of this complex system. Studying this phenomenon deepens our understanding of the energetic processes accompanying the formation of giant stars and helps clarify how jets regulate material accretion and remove excess angular momentum from the circumstellar disk.