Credit: NASA, ESA, CSA, T. Morishita (IPAC-Caltech), and A. Pagan (STScI)

The seven galaxies highlighted in this James Webb Space Telescope image have been confirmed to be at a distance that astronomers refer to as redshift 7.9, which correlates to 650 million years after the big bang. This makes them the earliest galaxies yet to be spectroscopically confirmed as part of a developing cluster.

Astronomers used the telescope’s Near-Infrared Spectrograph (NIRSpec) instrument to precisely measure the distances and determine that the galaxies are part of a developing cluster. Galaxy YD4, previously estimated to be at a further distance based on imaging data alone, was able to be more accurately placed at the same redshift as the other galaxies. Before Webb, astronomers did not have high resolution imaging or spectral infrared data available to do this type of science.

At extreme distances, astronomers use the redshift reference to account for the fact that, as the universe expands, wavelengths of light are stretched and “shifted” to redder wavelengths, which are longer. Shorter wavelengths, for example ultraviolet and X-ray, are toward the bluer end of the electromagnetic spectrum. So extreme distances in the early universe are referenced by how much the light emitted there has been shifted as it traveled through space to be detected by a telescope.

Provider: Space Telescope Science Institute

Image Source: https://webbtelescope.org/contents/news-releases/2023/news-2023-118

Curator: STScI, Baltimore, MD, USA

Image Use Policy: http://stsci.edu/copyright/