Webb reveals unseen objects in galaxy cluster 'El Gordo'

The distinct features captured by JWST  

One of the most remarkable features seen in Webb's image is "El Anzuelo", or "The Fishhook". El Anzuelo is a galaxy located 10.6 billion light-years away from Earth.

The galaxy can be seen as a bright red arc in the upper right corner of the image. 

The reddish hue of El Anzuelo arises from two factors: firstly, the presence of dust within the galaxy, and secondly, its significant distance, which causes cosmological redshift effects on the light waves.

Webb's observations deduced that this faraway galaxy is disk-shaped, with a diameter of around 26,000 light-years – one-fourth the size of the Milky Way.

Scientists also gained some insights into the history of star formation in the El Anzuelo galaxy. The powerful telescope was able to peer through the dust veils to image the galaxy’s center, where it observed that star production was rapidly dropping at the time. 

One remarkable feature of this cluster is the elongated, slender line that extends to the left of its center.

This structure, known as La Flaca, is one of the many lensed background galaxies seen in the Webb image. The light from this galaxy has traveled 11 billion years to be detected by the space telescope. 

Furthermore, the discovery of a single red giant star nicknamed Quyllur (Quechua word for star) stood out in Webb's observations. This is the first single red giant star spotted beyond one billion light-years from Earth. Hubble has previously identified lensed stars, but all of them were noted to be blue supergiants. 

“It's almost impossible to see lensed red giant stars unless you go into the infrared. This is the first one we’ve found with Webb, but we expect there will be many more to come,” Jose Diego of the Instituto de Física de Cantabria in Spain, lead author of one of the papers on El Gordo, said in a statement.

Gravitational lensing allowed Webb to detect galaxy cluster

The other features in the image include five multiple-lensed galaxies, which could be a young galaxy cluster that formed around 12.1 billion years ago. 

As per NASA, El Gordo was chosen to be studied by Webb due to its natural cosmic magnifying ability through gravitational lensing.

This phenomenon occurs when massive cosmic objects induce a deformation in space-time. It warps space around cosmic objects like galaxies, thereby magnifying and enlarging distant objects. 

“Lensing by El Gordo boosts the brightness and magnifies the sizes of distant galaxies. This lensing effect provides a unique window into the distant universe,” said Brenda Frye of the University of Arizona, and lead author of one of the papers.

The distinct features have been reported in four different papers in the Astrophysical Journal and Astronomy & Astrophysics.