James Webb telescope spies a monstrous molecular cloud shrouded in mystery — Space photo of the week

Stars form in molecular clouds — molecular clouds — regions that are cold, dense, rich in molecules and filled with dust. One enormous cloud responsible for forming half of the stars in the Milky Way's central region is the Sagittarius B2 (Sgr B2) molecular cloud, located a few hundred light-years from our central supermassive black hole.

Boasting a total mass between 3 million and 10 million times that of the sun and stretching 150 light-years across, it is one of the largest molecular clouds in the galaxy. It lies roughly 26,000 light-years from Earth, in the constellation Sagittarius. It is also chemically rich, with several complex molecules discovered so far.

But this giant star-forming region is shrouded in a mystery: how it has managed to produce 50% of the stars in the region, despite containing just 10% of the galactic center's gas.

Astronomers observed this super-efficient stellar factory using the James Webb Space Telescope (JWST), in the hope of finding some clues about its unusual productivity. This spectacular image is the telescope's mid-infrared view, captured by JWST's Mid-Infrared Instrument (MIRI).

In the image, the clumps of dust and gas in the molecular complex glow in shades of pink, purple and red. These clumps are seen surrounded by dark areas. Dark does not mean that these regions are empty or emit nothing; instead, light in these areas is blocked by dense dust that the instrument cannot detect.

In star-forming regions like this one, warm dust and gas and only the brightest stars emit in the mid-infrared. This contrasts with the near-infrared image captured simultaneously by JWST's Near-Infrared Camera (NIRCam), which reveals an abundance of stars because stars emit more strongly in the near-infrared light.

In this MIRI image, the clumps on the right that appear redder than the rest of the cloud complex correspond to one of the most chemically complex areas known, as revealed by previous observations using other telescopes. Astronomers think this unique region may hold clues to why Sgr B2 is more efficient at star formation than the rest of the galactic center.

Additionally, an in-depth analysis of the masses and ages of the stars in this stellar factory could reveal further insight into the star-forming mechanisms in the Milky Way's center.

For more sublime space images, check out our Space Photo of the Week archives.