NASA's James Webb Space Telescope has unveiled a breathtaking cosmic spectacle: an immense stellar jet spanning eight light-years, originating from a massive star within the Sharpless 2-284 nebula. This colossal eruption, twice the distance between our Sun and Alpha Centauri, is a remarkably rare occurrence, according to researchers. The jet, resembling a double-bladed lightsaber, streams across space at hundreds of thousands of miles per hour, powered by a protostar ten times the mass of our Sun, located 15,000 light-years away on the outskirts of the Milky Way.
The discovery was unexpected. Lead author Yu Cheng of the National Astronomical Observatory of Japan noted, "We didn't know this massive star with such a super-jet existed before this observation. Such a spectacular outflow of molecular hydrogen is rare in our galaxy." These highly collimated jets, composed of plasma, are essentially a star's spectacular birth announcement, representing the ejection of gas along the star's spin axis, likely influenced by magnetic fields. While hundreds of protostellar jets have been observed, primarily from lower-mass stars, this discovery offers invaluable insights into the formation of massive stars.
Co-author Jonathan Tan of the University of Virginia and Chalmers University of Technology expressed his astonishment at the jet's size, order, and symmetry. Webb's infrared imagery reveals detailed filamentary structures, indicating interaction with interstellar dust and gas, creating knots, bow shocks, and linear chains. The jet's tips, positioned in opposite directions, encapsulate the star's formation history, showcasing how material progressively moved outward over 100,000 years.
The proto-cluster hosting the jet, located almost twice as far from the galactic center as our Sun, is situated in the Milky Way's periphery, characterized by low metallicity (a lower abundance of elements heavier than hydrogen and helium). This pristine environment provides a local analog for studying the conditions of the early universe. Cheng explains that massive stars significantly influence galactic evolution, and this discovery illuminates the formation of such stars in low-metallicity environments, offering a window into the early cosmos.
Webb's observations strongly support the "core accretion" model of star formation, suggesting a relatively stable disk around the star, contrary to the "competitive accretion" model, which posits a more chaotic process. The jet's nearly 180-degree symmetry supports the core accretion theory. The presence of other potential massive stars in this region suggests further discoveries are possible. This research, accepted for publication in The Astrophysical Journal, represents a significant leap forward in understanding 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/
