A pair of galaxies with unique question mark shapes discovered

Another fascinating new image sent back from the world's most expensive space telescope, the James Webb Space Telescope, shows a galaxy shaped like a question mark. The reason for its unusual shape reveals an important truth about how the $10 billion telescope system looks at some of the most distant galaxies ever observed.

This question mark-shaped galaxy is actually part of an image of the galaxy cluster MACS-J0417.5-1154, which is so massive that it warps spacetime. Massive objects—in this case, clusters of multiple galaxies—exert such a strong gravitational pull that they warp space, causing light passing through them to stretch. It's like using a magnifying glass. In some cases, this effect, called gravitational lensing, can even cause the same galaxy to appear multiple times in different locations in a single image.

The specific case that led to this unique image is the result of Earth, the galaxy cluster, and the target galaxy all aligning, in a phenomenon known as hyperbolic gravitational lensing. There is actually a pair of galaxies here, but the lensing makes it appear five times, creating the question mark shape.

A pair of galaxies with unique question mark shapes discovered Picture 1

"We currently know of only three or four cases of similar gravitational lensing configurations in the observable universe. That fact makes this discovery exciting because it demonstrates the power of Webb and suggests that we will probably find many more such configurations now," astronomer Guillaume Desprez of Saint Mary's University in Halifax, Nova Scotia, said in a statement.

The image was taken with Webb's NIRCam instrument, but the researchers also used the space telescope's NIRISS system to determine where stars are forming, even in a galaxy billions of light years away. Star formation rates can increase when two galaxies are in the process of merging or colliding.

'Knowing when, where, and how stars form in galaxies is crucial to understanding how galaxies have evolved over the history of the universe,' said astronomer Vicente Estrada-Carpenter of Saint Mary's University. 'Both question mark galaxies show active star formation in some compact regions, possibly the result of gas from the colliding galaxies. However, neither of their shapes has been disrupted too much, so we may be seeing the beginnings of interactions between them.'

Aside from their strange shapes, the galaxies seen here are useful simulations of what our galaxy might have looked like when it was "young."

Jessica Tanner

Update 23 December 2024