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last mo.

Webb Resolves 16.5 Million Stars in Nearby Starburst Galaxy M82

A 65-hour NIRCam infrared exposure gives astronomers the data to map stellar ages and reconstruct how a past encounter with M81 triggered M82’s brief, intense starburst.

Edge-on view of the Cigar Galaxy, Messier 82, its bright disk crossed by red plumes of gas and dust
This Webb image shows the edge-on spiral galaxy Messier 82. Image credit: NASA / ESA / CSA / Adam Smercina, STScI, Tufts / Thomas Williams, University of Manchester / Alyssa Pagan, STScI.

Overview

  • In late June 2026, JWST’s Near‑Infrared Camera completed a 65‑hour Cibola survey image that pierced M82’s dust and resolved roughly 16.5 million individual stars in the galaxy.
  • The infrared view reveals a lopsided, distorted disk and layered, hourglass‑shaped plumes of material with ionized gas close to the disk and drifting dust farther out.
  • Astronomers say the asymmetry is consistent with a past gravitational interaction with nearby M81 that funneled gas inward and ignited star formation at about ten times the Milky Way’s rate for a galaxy of M82’s size.
  • Researchers are now using the resolved stars together with Hubble and other data to measure star ages and positions so they can reconstruct the timing and duration of the starburst and the interaction history.
  • Because M82 is nearby and extreme, the dataset will let scientists test how galaxy encounters and feedback from young stars and supernovae drive short, self‑limiting bursts of star formation and will inform future studies of dusty, crowded galaxies.