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One of the greatest strengths of the NASA/ESA/CSA James Webb Space Telescope is its ability to give astronomers detailed views of areas where new stars are being born. The latest example is NGC 346, the brightest and largest star-forming region in the Small Magellanic Cloud, showcased here in a new image from Webb’s innovative Mid-Infrared Instrument (MIRI), half of which was provided by Europe.
The Small Magellanic Cloud (SMC) is a satellite galaxy of the Milky Way, visible to the unaided eye in the southern constellation Tucana. This small companion galaxy is more primitive than the Milky Way in that it possesses fewer heavy elements, which are forged in stars through nuclear fusion and supernova explosions, compared to our own galaxy.
Since cosmic dust is formed from heavy elements like silicon and oxygen, scientists expected the SMC to lack significant amounts of dust. However the new MIRI image, as well as a previous image of NGC 346 from Webb’s Near-Infrared Camera released in January, show ample dust within this region.
In this representative-colour image, blue tendrils trace emission from material that includes dusty silicates and sooty chemical molecules known as polycyclic aromatic hydrocarbons, or PAHs. More diffuse red emission shines from warm dust heated by the brightest and most massive stars in the heart of the region. An arc at the centre left may be a reflection of light from the star near the arc’s centre (similar, fainter arcs appear associated with stars at lower left and upper right). Lastly, bright patches and filaments mark areas with abundant numbers of protostars. The research team has detected 1001 pinpoint sources of light, most of them young stars still embedded in their dusty cocoons.
This image includes 7.7-micron light shown in blue, 10 microns in cyan, 11.3 microns in green, 15 microns in yellow, and 21 microns in red (770W, 1000W, 1130W, 1500W, and 2100W filters, respectively).
By combining Webb data in both the near-infrared and mid-infrared, astronomers are able to take a fuller census of the stars and protostars within this dynamic region. The results have implications for our understanding of galaxies that existed billions of years ago, during an era in the universe known as 'cosmic noon', when star formation was at its peak and heavy element concentrations were lower, as seen in the SMC.
This new image taken by Webb’s Mid-Infrared Instrument (MIRI) complements Webb’s view of NGC 346 as seen by the (NIRCam), released in January 2023.
Image description: The lower half of this image contains arcs of bluish material that form a boat-like shape. One end of these arcs points to the top right of the image, while the other end points toward the bottom left. Another plume of blue filaments expands from the centre to the top left, resembling the mast of a sailboat. Within and extending beyond the boat shape are translucent curtains of pink, which cover most of the image. Stars are noticeably scarce. A couple dozen bright pink patches with six short diffraction spikes are scattered within the blue filaments. Many faint blue dots, or stars, also speckle the background, which is black or dark grey.
