James Webb Space Telescope Discovery

A Spiral Amongst Thousands

A crowded field of galaxies throngs this Picture of the Month from the NASA/ESA/CSA James Webb Space Telescope, along with bright stars crowned with Webb’s signature six-pointed diffraction spikes. The large spiral galaxy at the base of this image is accompanied by a profusion of smaller, more distant galaxies which range from fully-fledged spirals to mere bright smudges. Named LEDA 2046648, it is situated a little over a billion light-years from Earth, in the constellation Hercules. One of Webb’s principle science goals is to observe distant galaxies in the early universe to understand the details of their formation, evolution, and composition. Webb’s keen infrared vision helps the telescope peer back in time, as the light from these distant galaxies is redshifted towards infrared wavelengths. Comparing these systems with galaxies in the local universe will help astronomers understand how galaxies grew to form the structure we see today. Webb will also probe the chemical composition of thousands of galaxies to shed light on how heavy elements were formed and built up as galaxies evolved. To take full advantage of Webb’s potential for galaxy archeology, astronomers and engineers must first calibrate the telescope’s instruments and systems. Each of Webb’s instruments contains a labyrinthine array of mirrors and other optical elements that redirect and focus starlight gathered by Webb’s main mirror. This particular observation was part of the commissioning campaign for Webb’s Near-InfraRed Imager and Slitless Spectrograph (NIRISS). As well as performing science in its own right, NIRISS supports parallel observations with Webb’s Near-InfraRed Camera (NIRCam). NIRCam captured this galaxy-studded image while NIRISS was observing the white dwarf WD1657+343, a well-studied star. This allows astronomers to interpret and compare data from the two different instruments, and to characterise the performance of NIRISS. Credit: ESA/Webb, NASA & CSA, A. Martel This image displays a wider view of the field of stars and galaxies surrounding the spiral galaxy LEDA 2046648. Webb’s NIRCam instrument has picked out a profusion of smaller, more distant galaxies and bright stars around this galaxy, demonstrating the telescope’s impressive resolution in infrared wavelengths. Calibration images such as this one were critical to verify the telescope’s capabilities as it was prepared for science operations, and this one doesn’t disappoint.
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