Emissions from young protostars are mostly molecules, Web astronomers find

Herbig-Harrow (HH) objects form when jets of gas ejected from stellar winds or protostars collide at high speed with nearby gas and dust, creating shock waves. Astronomers using the NASA/ESA/CSA James Webb Space Telescope have made infrared observations of HH 211, a 10,000-year-old analog of our Sun.

This web image shows the Herbic-Harrow object HH ​​211, located 1,000 light-years away in the constellation Perseus. Image credit: NASA / ESA / CSA / Webb / T. Ray, Dublin Institute for Advanced Studies.

HH 211Otherwise known as Per-Emp 1 and Polo 103, it is 1,000 light-years away in the constellation Perseus.

In this context, A A class 0 protostarA baby solar-type star has about 8% the mass of the present-day Sun.

A new high-resolution, near-infrared image of HH 211 was obtained by the Infrared Camera (NIRCam) on the NASA/ESA/CSA James Webb Space Telescope.

„Infrared imaging is powerful for studying newborn stars and their outflows because such stars are invariably embedded in the gas from the molecular cloud from which they formed,” Webb astronomers said in a statement.

„The star’s outgoing infrared emission penetrates obscured gas and dust, making a Herbic-Harrow object like HH 211 ideal for observation with the Web’s sensitive infrared instruments.”

„Molecules excited by turbulent conditions, including molecular hydrogen, carbon monoxide, and silicon monoxide, emit infrared light that Webb can collect to map the structure of their exit.”

An image of HH 211 shows a series of bow shocks to the southeast (bottom-left) and northwest (top-right) and the narrow dipole jet driving them.

„The web reveals this scene in an unprecedented way – with about 5 to 10 times higher spatial resolution than previous images of HH 211,” the astronomers said.

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„The inner jet is observed to 'wobble’ with mirror symmetry on either side of the central protostar.”

„This agrees with small-scale observations and suggests that the protostar may indeed be an unresolved binary star.”

Previous observations of HH 211 with ground-based telescopes revealed giant bow shocks moving away from us (northwest) and toward us (southeast), cavity-like structures in shocked hydrogen and carbon monoxide, as well as a knotted and wobbly dipole. jet in silicon monoxide.”

The researchers determined that the outflow of material was relatively slow compared to more evolved protostars with similar outflow types.

They measured the velocity of the outflow structures to be approximately 80–100 km/s (48–60 miles/s).

However, the difference in velocity between these segments of the outflow and the leading material they collide with – the shock wave – is very small.

„The outflows from the younger stars at the core of H211 are mostly composed of molecules because the relatively low shock wave velocities are not powerful enough to break molecules into simpler atoms and ions,” the authors concluded.

theirs Paper Published in the magazine Nature.


DB Ray and many others. Emissions from younger stars are mostly molecules. Nature, published online August 24, 2023; doi: 10.1038/s41586-023-06551-1

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