Mapping Molecular Structure in Supersonic Outflow with NASA’s James Webb Space Telescope
The James Webb Space Telescope, operated by NASA, has captured a remarkably detailed image of Herbig-Haro 211 (HH 211), a bipolar jet racing through interstellar space at supersonic velocities. Located approximately 1,000 light-years away in the Perseus constellation, HH 211 is among the youngest and closest protostellar outflows, making it an ideal subject for Webb’s observations.
Young Star’s Supersonic Outflow Snapped by Webb
Herbig-Haro (HH) objects are radiant regions encircling newly formed stars, created when the intense stellar winds or gas jets expelled from these young stars collide with nearby gas and dust at high speeds. The image of HH 211, captured by NASA’s James Webb Space Telescope, unveils an outflow originating from a Class 0 protostar. This protostar is akin to our Sun when it was a mere few tens of thousands of years old and possessed only 8% of its current mass. (Over time, it will mature into a Sun-like star.)
Infrared Imaging and Stellar Outflows
Infrared imaging proves exceptionally effective in studying nascent stars and their outflows, as these stars are often still enshrouded within the molecular clouds where they formed. Infrared emissions from the star’s outflows penetrate through the obstructing gas and dust, rendering Herbig-Haro objects like HH 211 ideal candidates for observation using Webb’s highly sensitive infrared instruments. Molecules, excited by the turbulent conditions, such as molecular hydrogen, carbon monoxide, and silicon monoxide, emit infrared light that Webb can collect to meticulously chart the structure of these outflows.
Webb’s Remarkable Observations
The image reveals a sequence of bow shocks in the southeast (lower-left) and northwest (upper-right), along with the slender bipolar jet propelling them. Webb’s observations offer an unparalleled level of detail, with spatial resolution approximately 5 to 10 times higher than any previous HH 211 images. The inner jet displays a symmetrical “wiggle” on either side of the central protostar, consistent with observations on smaller scales, hinting that the protostar might actually be an unresolved binary star system.
Previous Observations and Research Findings
Earlier observations of HH 211 using ground-based telescopes unveiled large bow shocks moving both away from us (northwest) and toward us (southeast). These observations also disclosed cavity-like structures in shocked hydrogen and carbon monoxide, in addition to a complex, twisting bipolar jet in silicon monoxide. Webb’s new data has allowed researchers to determine that HH 211’s outflow is relatively slow compared to more developed protostars with similar outflows.
The research team measured velocities of the innermost outflow components at approximately 48-60 miles per second (80 to 100 kilometers per second). However, the velocity difference between these outflow segments and the leading material they collide with, the shock wave, is notably smaller. This led the scientists to conclude that the outflows from the youngest stars, like the one at the heart of HH 211, consist primarily of molecules. The relatively low shock wave velocities are insufficient to break down these molecules into simpler atoms and ions.
About the James Webb Space Telescope
The James Webb Space Telescope stands as the world’s premier space science observatory, unraveling mysteries within our solar system, exploring distant exoplanets, and probing the enigmatic structures and origins of our universe. Webb is an international endeavor spearheaded by NASA in collaboration with the ESA (European Space Agency) and the Canadian Space Agency.