Webb Telescope Snaps Photos of 19 Spiral Galaxies


The James Webb Space Telescope (JWST), launched in 2021, has captured and released new images of 19 spiral galaxies located near our Milky Way. These images were made public by the team of scientists working on the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) project which involves several major astronomical observatories. The images offer fresh insights into star formation, galaxy structure, and evolution.

The closest of the 19 galaxies viewed, NGC5068, is approximately 15 million light years away from Earth, while the most distant, NGC1365, is about 60 million light years away. To put it into perspective, a light year is the distance light travels in a year, approximately 9.5 trillion kilometers.

The JWST, which commenced data collection in 2022, has been instrumental in shaping our understanding of the early universe through its pictures of space. Unlike the Hubble Space Telescope, which was launched in 1990 and is still operational, observing the universe predominantly at optical and ultraviolet wavelengths, the JWST primarily uses infrared to gaze at the universe.

Spiral galaxies, such as our Milky Way, are a common type of galaxy. The newly released images, captured by Webb’s Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI), showcase approximately 100,000 star clusters and millions, or possibly billions, of individual stars.

University of Oxford astronomer Thomas Williams, who led the team’s data processing on the images, emphasized the importance of these data. According to him, they provide a novel perspective on the earliest phase of star formation. Stars are born within dense, dusty clouds that totally obstruct light at visible wavelengths, which the Hubble Space Telescope can detect. However, these clouds are illuminated at the JWST wavelengths, a phase about which we have limited knowledge.

Williams further explained that about half of spiral galaxies have a bar-like structure emanating from the center, to which the spiral arms are attached. The prevalent belief is that galaxies form from the inside out, thereby increasing in size over their lifetimes.

The images from JWST have allowed scientists, for the first time, to examine the structure of the dust and gas clouds where stars and planets are born, in great detail. These images are of galaxies located beyond the Large Magellanic Cloud and Small Magellanic Cloud, which are in proximity to the Milky Way.

Erik Rosolowsky, an astronomer at Canada’s University of Alberta, elaborated on how Webb’s observations have built on Hubble’s. With Hubble, we were able to see the starlight from galaxies, but some of it was obscured by the galaxy’s dust. This limitation hindered our understanding of how a galaxy functions as a system. However, Webb’s view in the infrared allows us to see through this dust to observe stars located behind and within this enveloping dust. This breakthrough has significantly advanced our understanding of galaxies and the universe.



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