Herbig-harrows are luminous regions surrounding young stars. They form when stellar winds or jets of gas ejected from these stars create shock waves that collide at high speeds with nearby gas and dust.
The James Webb Space Telescope captured a high-resolution image of HH 211, a bipolar jet moving through interstellar space at supersonic speeds. The object, located about a thousand light-years from Earth in the Perseus group, is one of the youngest and closest protostellar jets, making it an ideal target for Webb.
Webb's close-up, high-resolution view of Herbig-Haro 211 reveals excellent details of the young star's jet.
Credit: ESA/Webb, NASA, CSA, Tom Ray (Dublin)
Herbig-harrows are luminous regions surrounding young stars. They form when stellar winds or jets of gas ejected from these stars create shock waves that collide at high speeds with nearby gas and dust. This image of HH 211 taken by NASA's James Webb Space Telescope reveals a jet from a Type 0 protostar, a childhood counterpart of our Sun when it was no more than a few tens of thousands of years old and with a mass of only 8% of today's Sun. (It will eventually grow into a star like the sun).
AA photography is particularly effective in studying contemporary stars and their jets, because these stars are in any case still inside the gas from the molecular cloud in which they were formed. The AA emission from the star's jets penetrates the obscuring gas and dust, so Webb's sensitive AA instruments are ideal for observing Herbig-Harrow objects like HH 211. Molecules excited by the turbulent conditions, including molecular hydrogen, carbon monoxide and silicon monoxide , emit light AA that Webb can collect to map the structure of the jets.
The image shows a series of arc shock waves in the southeast (bottom left) and northwest (top right) and also the narrow bipolar jet that drives them. Webb reveals this scene in unprecedented detail - the spatial resolution is approximately five to ten times higher than any previous images of HH 211. The inner jet appears to "oscillate" in mirror symmetry on both sides of the protostar. This is suitable for smaller scale observations and is enhanced by the fact that the progenitor is actually possibly a binary star.
Previous observations of HH 211 using ground-based telescopes have revealed giant arcuate shock waves moving away from us (northwest) and approaching us (southeast) and cavity-like structures in hydrogen and carbon monoxide, respectively, that have been traversed by both a shock wave and an entangled and oscillating dipole jet in mono-silicon Oxidized. Researchers used Webb's new observations to determine that the object's jet is relatively slow compared to more evolved protostars with similar types of jets.
The team measured and found that the velocities of the structures of the innermost jet are about 80 to 100 kilometers per second. But, the difference in speed between these parts of the jet and the carrier material they collide with - the shock wave - is much smaller. The researchers concluded that jets from the youngest stars, like the one at the center of HH 211, are mostly composed of molecules, because the relatively low speeds of the shock waves do not have enough energy to break the molecules into simpler atoms and ions.
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