Webb notices a Globular Cluster with Individual Stars.

The James Webb Space Telescope spent slightly over an hour on June 20, 2022, peering at Messier 92 (M92), a globular cluster 27,000 light-years away in the Milky Way halo. The discovery, one of Webb's very first science observations, is part of Early Release Science (ERS) program 1334, one of 13 ERS programs meant to help astronomers understand how to use Webb and maximize its scientific capabilities.

Image credit: NASA, ESA, CSA, A. Pagan (STScI).

Webb's NIRCam sensor obtained this detail of the globular cluster M92. This field of vision encompasses the lower left quarter of the image's right half. Globular clusters are dense clumps of closely packed stars that formed all at once. M92 contains approximately 300,000 stars packed into a ball roughly 100 light-years across. The night sky of a planet in the center of M92 would be illuminated by thousands of stars thousands of times brighter than those in our own sky. The image depicts stars at various distances from the cluster's core, which aids scientists in understanding the motion of the stars and the mechanics of that motion.

M92 is a typical globular cluster with implications for star evolution and stellar systems. It is one of the Milky Way's oldest globular clusters, estimated to be between 12 and 13 billion years old, and contains some of the galaxy's oldest stars. It is also exceedingly dense, allowing Webb to measure stars that are extremely close together.

 

Webb and Hubble operate at longer wavelengths, allowing us to observe very cool stars. We were able to reach down to the lowest mass stars, which is close to the boundary where stars stop being stars. Webb is also faster than Hubble, taking just a few hours to detect these faint stars. This is encouraging to see that we were still able to detect such small, faint stars without trying too hard.

Image credit: NASA, ESA, CSA, A. Pagan (STScI).

 

The NIRCam instrument of the James Webb Space Telescope acquired this image of the globular cluster M92. The black strip in the center represents a chip gap caused by the separation of NIRCam's two long-wavelength detectors. The gap covers the cluster's dense center, which is too bright to capture at the same time as the fainter, less dense surrounds.  The image covers around 5 arcminutes or 39 light-years.

 

Webb's NIRCam sensor obtained this detail of the globular cluster M92. This field of vision encompasses the lower left quarter of the image's right half. Globular clusters are dense clumps of closely packed stars that formed all at once. M92 contains approximately 300,000 stars packed into a ball roughly 100 light-years across. The night sky of a planet in the center of M92 would be illuminated by thousands of stars thousands of times brighter than those in our own sky. The image depicts stars at various distances from the cluster's core, which aids scientists in understanding the motion of the stars and the mechanics of that motion.