James Webb Space Telescope reveals the thick cosmic dust of Sagittarius B2, the giant star-forming cloud in the Milky Way – Space Photo of the Week

Why is it so special: The stars in the Milky Way galaxy are born from giant molecular clouds. The biggest one is Sagittarius B2. This is only hundreds of light years from the Galaxy central black hole (known as Sagittarius A*). This black hole is much richer than you first think – it has 10% of the galaxy-centric gas, but accounts for about half of the ongoing star formation in the region. The reason for the extremely unbalanced star formation within the central galactic region is a challenge for scientists.

Queue James Webb Space Telescope (JWST). This has recently been observed in two wavelength light, and helps astronomers find out why. This breathtaking new image of molecular clouds (above) comes from JWST’s near-infrared camera (NIRCAM). In it you can see the stars glow brightly between the orange clouds of gas and the dust.

However, even within the infrared spectrum, the differences in what can be seen are substantial, as evidenced by another image in the cloud by JWST mid-infrared instruments (MIRI).

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Miri’s image is completely different, revealing dust clouds in the region illuminated by the stars. It shows pink and purple clouds surrounded by very dark areas scattered with stars. JWST can’t see everything: Even its infrared vision cannot penetrate the dense clouds. This remains dark and opaque in the image of Milli. What is hidden from sight in these areas is the raw material of the stars.

Why Sagittarius B2 is much more productive than the rest of the galaxy centre remains inexplicable, but there are clues. To the right of the millimeter image is a very bright, red area known to be rich in molecular material. It could hold the key to why the cloud outweighs star generation across the galaxy centre, and could reconstruct theories of galaxy growth and evolution. Scientists will use Webb’s new data on Sagittarius B2 to understand how long it was forming the star and whether certain events caused prolific activity.

For sublime space images, see Space Photos in this week’s archives.