This image was captured by JWST’s NIRCam, or Near-InfraRed Camera. NIRCam makes observations in the near-infrared, which spans wavelengths of light that are just longer than optical wavelengths. Like MIRI, it is equipped with a range of filters that cover its wavelength range of 0.6 to 5 micrometers, including 29 filters specifically intended for imaging. Data collected through eight of those filters were used to complete this impressive image, which picks out light emitted from the wealth of stars that might be obscured by dust at other wavelengths. Even though stars do not emit the majority of their light in the infrared, optical light is much more vulnerable to being scattered by dust than infrared light is, and so infrared instruments like Webb can provide the best opportunities to study stars in regions (like galaxies) that might also contain large amounts of dust.
The bright red-pink spots correspond to regions rich in ionized hydrogen, which is due to the presence of newly formed stars. The diffuse gradient of blue light around the central region shows the distribution of older stars. The compact light blue regions within the red, ionized gas, mostly concentrated in the spiral arms, show the distribution of young star clusters.
The open cluster Westerlund 1, is located roughly 12,000 light-years away in the southern constellation Ara (the Altar) where it resides behind a huge interstellar cloud of gas and dust. It was discovered in 1961 from Australia by Swedish astronomer Bengt Westerlund. Westerlund 1 is an incomparable natural laboratory for the study of extreme stellar physics, helping astronomers to find out how the most massive stars in our Galaxy live and die.
The unique draw of Westerlund 1 is its large, dense, and diverse population of massive stars, which has no counterpart in other known Milky Way galaxy clusters in terms of the number of stars and the richness of spectral types and evolutionary phases. All stars identified in this cluster are evolved and very massive, spanning the full range of stellar classifications including Wolf-Rayet stars, OB supergiants, yellow hypergiants (nearly as bright as a million Suns) and luminous blue variables. Because such stars have a rather short life, Westerlund 1 is very young, astronomically speaking. Astronomers estimate the cluster’s age to be somewhere between 3.5 and 5 million years (its exact age is still a matter of debate), making it a newborn cluster in our galaxy. In the future, it is believed that it will likely evolve from an open cluster into a globular cluster. These are roughly spherical, tightly packed collections of old stars bound together by gravity.
This image shows the center of the Serpens Nebula as seen by the NASA/ESA/CSA JWST’s Near-InfraRed Camera (NIRCam).
The Serpens Nebula, located 1300 light-years from Earth, is home to a particularly dense cluster of newly forming stars (about 100 000 years old), some of which will eventually grow to the mass of our Sun. Webb’s image of this nebula revealed a grouping of aligned protostellar outflows (seen in the top left). These jets are identified by bright clumpy streaks that appear red, which are shock waves caused when the jet hits the surrounding gas and dust.
Throughout this image filaments and wisps of different hues represent reflected starlight from still-forming protostars within the cloud. In some areas, there is dust in front of that reflection, which appears here in an orange, diffuse shade.
A high-definition image from the NASA/ESA/CSA JWST’s NIRCam (Near-Infrared Camera) unveils intricate details of supernova remnant Cassiopeia A (Cas A), and shows the expanding shell of material slamming into the gas shed by the star before it exploded.
The most noticeable colours in Webb’s newest image are clumps of bright orange and light pink that make up the inner shell of the supernova remnant. These tiny knots of gas, composed of sulphur, oxygen, argon, and neon from the star itself, are only detectable thanks to NIRCam’s exquisite resolution, and give researchers a hint at how the dying star shattered like glass when it exploded.
The outskirts of the main inner shell look like smoke from a campfire. This marks where ejected material from the exploded star is ramming into surrounding circumstellar material. Researchers have concluded that this white color is light from synchrotron radiation, which is generated by charged particles traveling at extremely high speeds and spiraling around magnetic field lines.
There are also several light echoes visible in this image, most notably in the bottom right corner. This is where light from the star’s long-ago explosion has reached, and is warming, distant dust, which glows as it cools down.