NASA's James Webb Space Telescope has captured an unprecedented image of a colossal stellar jet emanating from a massive star located 15,000 light-years away in the outer regions of our Milky Way galaxy. Spanning an astonishing 8 light-years – twice the distance to Alpha Centauri – this double-lobed jet, residing within the Sharpless 2-284 (Sh2-284) nebula, is a remarkably rare and significant discovery.
The jet, resembling a cosmic lightsaber, is propelled by a protostar with a mass ten times that of our Sun. Its immense scale and power surprised researchers, who hadn't previously identified such a massive star with this type of super-jet in this region of the galaxy. This serendipitous observation offers valuable insights into the formation of massive stars.
While hundreds of protostellar jets have been observed, most originate from low-mass stars. This particular jet's size provides compelling evidence that the scale of these outflows directly correlates with the mass of the central star. The more massive the star, the larger and more energetic the jet.
Webb's high-resolution infrared imagery reveals a detailed filamentary structure within the jet, indicating its interaction with interstellar dust and gas. This interaction creates distinct knots, bow shocks, and linear chains, effectively mapping the history of the star's formation. The jet's tips, pointing in opposite directions, represent the furthest extent of the outflow over a period exceeding 100,000 years.
The location of this stellar nursery on the outskirts of the Milky Way is also notable. The low metallicity (low abundance of elements heavier than hydrogen and helium) of Sh2-284 provides a unique environment that mirrors conditions in the early universe. This makes it an invaluable tool for studying star formation in low-metallicity environments and understanding how massive stars influence galactic evolution.
The detailed observations support the 'core accretion' theory of massive star formation, suggesting a relatively stable disk surrounding the star. This contrasts with the 'competitive accretion' model, which postulates a more chaotic process. The jet's remarkable symmetry, with its lobes nearly 180 degrees apart, strongly supports the core accretion model. Further analysis indicates the central star is approximately ten times the mass of our Sun and continues to grow.
This discovery is not isolated. Other potential stellar cores in earlier developmental stages have been identified within the Sh2-284 cluster, suggesting further opportunities for future research using the James Webb Space Telescope to unravel the mysteries of massive star formation.
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Originally published at: https://science.nasa.gov/missions/webb/nasas-webb-observes-immense-stellar-jet-on-outskirts-of-our-milky-way/
