NASA’s James Webb Space Telescope’s high resolution, near-infrared look at Herbig-Haro 211 reveals exquisite detail of the outflow of a young star, an infantile analogue of our Sun. Herbig-Haro objects are formed when stellar winds or jets of gas spewing from newborn stars form shock waves colliding with nearby gas and dust at high speeds. The image showcases a series of bow shocks to the southeast (lower-left) and northwest (upper-right) as well as the narrow bipolar jet that powers them in unprecedented detail. Molecules excited by the turbulent conditions, including molecular hydrogen, carbon monoxide and silicon monoxide, emit infrared light, collected by Webb, that map out the structure of the outflows. Credits: ESA/Webb, NASA, CSA, T. Ray (Dublin Institute for Advanced Studies)
Herbig-Haro (HH) objects are
luminous regions surrounding newborn stars, formed when stellar winds or jets
of gas spewing from these newborn stars form shock waves colliding with nearby
gas and dust at high speeds. This image of HH 211 from NASA’s James Webb Space
Telescope reveals an outflow from a Class 0 protostar, an infantile analog of
our Sun when it was no more than a few tens of thousands of years old and with
a mass only 8% of the present-day Sun (it will eventually grow into a star like
the Sun).
Infrared imaging is powerful in
studying newborn stars and their outflows, because such stars are invariably
still embedded within the gas from the molecular cloud in which they formed.
The infrared emission of the star’s outflows penetrates the obscuring gas and
dust, making a Herbig-Haro object like HH 211 ideal for observation with Webb’s
sensitive infrared instruments. Molecules excited by the turbulent conditions,
including molecular hydrogen, carbon monoxide, and silicon monoxide, emit
infrared light that Webb can collect to map out the structure of the outflows.
The image showcases a series of bow
shocks to the southeast (lower-left) and northwest (upper-right) as well as the
narrow bipolar jet that powers them. Webb reveals this scene in unprecedented
detail — roughly 5 to 10 times higher spatial resolution than any previous
images of HH 211. The inner jet is seen to “wiggle” with mirror symmetry on
either side of the central protostar. This is in agreement with observations on
smaller scales and suggests that the protostar may in fact be an unresolved
binary star.
Earlier observations of HH 211 with
ground-based telescopes revealed giant bow shocks moving away from us
(northwest) and moving towards us (southeast) and cavity-like structures in
shocked hydrogen and carbon monoxide respectively, as well as a knotty and
wiggling bipolar jet in silicon monoxide. Researchers have used Webb’s new
observations to determine that the object’s outflow is relatively slow in
comparison to more evolved protostars with similar types of outflows.
The team measured the velocities of
the innermost outflow structures to be roughly 48-60 miles per second (80 to
100 kilometers per second). However, the difference in velocity between these
sections of the outflow and the leading material they’re colliding with — the
shockwave — is much smaller. The researchers concluded that outflows from the
youngest stars, like that in the center of HH 211, are mostly made up of
molecules, because the comparatively low shock wave velocities are not
energetic enough to break the molecules apart into simpler atoms and ions.
The James Webb Space Telescope is the world's premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.
Source: NASA’s Webb Snaps Supersonic Outflow of Young Star | NASA
No comments:
Post a Comment