Webb and Hubble team up to view massive galaxy cluster

13 Nov 2023

The galaxy cluster MACS0416 image created by combining observations from the James Webb Space Telescope and the Hubble Space Telescope. Image: NASA, ESA, CSA, STScI, Jose M Diego (IFCA), Jordan C J D'Silva (UWA), Anton M Koekemoer (STScI), Jake Summers (ASU), Dr Rogier Windhorst (ASU), Prof Haojing Yan (University of Missouri)

NASA said the detailed image was only possible thanks to the combined power of the two space telescopes, which also spotted a massively-magnified star system in the image.

Two of the most powerful space telescopes in the world – James Webb and Hubble – have teamed up to provide a stunning image of a distant cluster of galaxies.

The two machines turned their gazes to MACS0416, a galaxy cluster located roughly 4.3bn light-years from Earth. This means that the visible light left the cluster shortly after our own solar system was formed, according to NASA.

The cluster magnifies the light from more distant background galaxies due to gravitational lensing, which means researchers have been able to identify magnified supernovae and even individual stars from the image.

A similar effect was visible in James Webb’s first deep field image, which was able to see distant galaxies thanks to the mass of a galaxy cluster acting as a gravitational lens.

NASA said the latest image was only possible thanks to the power of both telescopes, as it combines infrared observations from the James Webb with visible-light data from the Hubble Space Telescope. Webb was able to bolster earlier looks into the galaxy by gazing further with its infrared equipment.

To make the image, the shortest wavelengths of light were colour-coded blue, while intermediate wavelengths are green and the longest wavelengths are red. The bluest galaxies are best detected by the Hubble, while the redder galaxies tend to be more distant and better detected by Webb’s instruments.

Two different images of a distant galaxy cluster, with different levels of detail and light in each image.

A comparison image of the MACS0416 galaxy cluster, with Hubble’s image on the left and James Webb’s image on the right. Image: NASA, ESA, CSA, STScI

The goal of this new image was to search for objects that vary in observed brightness over time, which are known as transients, according to NASA. A research team identified 14 transients across this image.

Prof Haojing Yan, a lead author of one paper which describes the results of the image, said researchers are referring to the cluster as the “Christmas Tree Galaxy Cluster”, due to the range of colours and the flickering lights visible within it.

NASA said that finding so many transients over a relatively short time frame suggests that astronomers could find many additional transients in this cluster and others like it.

A monstrous star system

One star system in particular has intrigued researchers due to its massive size, being dubbed Mothra – a monster from Japanese cinema. This star system is located in a galaxy that existed about 3bn years after the big bang and is magnified by a factor of at least 4,000 in the image.

NASA said the most likely explanation for the intense level of magnification is that there is an additional object within the cluster that is adding more magnification, but may be too faint for either telescope to see directly.

Hubble is one of the largest space telescopes created and is the predecessor of the James Webb Space Telescope, which is continuing the mission to gaze into the cosmos.

Last year, the two titan space telescopes teamed up to capture the result of NASA’s successful Double Asteroid Redirection Test (DART). The space telescopes took simultaneous observations of the collision as the DART spacecraft crashed into its target asteroid Dimorphos.

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Leigh Mc Gowran is a journalist with Silicon Republic