Webb reveals hidden galaxy populations in revisited deep field
by Erica Marchand
Paris, France (SPX) Aug 05, 2025

Webb has returned to the iconic Hubble Ultra Deep Field, providing astronomers with an unprecedented mid-infrared perspective of one of the most studied regions in the sky. Using nearly 100 hours of observation time with its Mid-Infrared Instrument (MIRI), the NASA/ESA/CSA James Webb Space Telescope has delivered its deepest extragalactic view in a single filter to date.

This area, known as the MIRI Deep Imaging Survey (MIDIS) region, combines data from both MIRI and the Near-Infrared Camera (NIRCam). The resulting image reveals more than 2500 galaxies, many of which are extremely red and previously undetected. These include dusty, massive systems and evolved galaxies that formed in the early Universe, now visible thanks to Webb's sharp mid-infrared resolution.

Webb's data offers critical insight into how light is distributed within these galaxies, allowing researchers to study their formation and evolutionary processes across cosmic time. The image's colors distinguish various galaxy characteristics: red and orange hues indicate intense dust or activity like starburst regions or active galactic nuclei, while greenish-white galaxies represent the most distant and redshifted populations. Most others appear in blue or cyan, marking their brightness in near-infrared wavelengths.

With this fresh look, Webb not only builds upon the deep field legacy established by Hubble but also opens new frontiers in understanding the Universe's earliest structures.

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