Images of spiral galaxies captured by the James-Webb telescope deciphered by an astronomer


Spiral galaxies are among the most mesmerizing celestial objects. This is evidenced by a new delivery of images collected by the James-Webb Space Telescope (JWST), put online Monday January 29. This telescope from NASA, the European (ESA) and Canadian (CSA) space agencies observes the Universe in infrared. This fringe of the light spectrum has the particularity of being able to p through certain dusty areas of the sky, which remained opaque to the Hubble telescope.

These new images are part in a long-term project, the international program High angular resolution physics in nearby galaxies (Phangs), in which Hubble and several terrestrial observatories were already participating, such as Alma and Muse of the Very Large Telescope (VLT), in Chile. “With the JWST, we can access a level of detail that we could not dream of beforerejoices Médéric Boquien (University and Observatory of the Côte d’Azur), who is participating in the Phangs collaboration. It’s revolutionary, and it raises new questions every time. » These nineteen new images will help to refine the understanding of the dynamics of these galaxies and the formation, within them, of billions of stars.

Review of some of them, the characteristics of which are commented on by Médéric Boquien.

NGC 628

The galaxy NGC 628 seen by the James Webb space telescope.
Composite image of the galaxy NGC 628, as seen by the James Webb (top left) and Hubble (bottom right) space telescopes.

“This galaxy presents itself from the front. In the image from the Hubble telescope, lower right, we observe darker regions made up of dust which attenuates the light of the stars, forming a sort of skeleton. We also see pinker areas, made of ionized gas where the most mive stars were formed, which explode after only a few million years of existence.

The James Webb [image du haut] reveals orange regions, which betray dust which glows red, heated by the light of the surrounding stars. The brightest regions are veritable nurseries, where stars born at most a few million years ago – practically today in astronomical terms – are hatching from their dust cocoons.

What particularly struck us when we received this image were the dark bubbles, which represent areas where star explosions have occurred. These have pushed back gas and dust which, compressed on their periphery, constitute strings of regions where new generations of stars are formed.

In the center there is a supermive black hole, which, here, is quiet. »

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