Oldest ‘dead galaxy’ yet is spotted by James Webb Telescope

Oldest ‘dead galaxy’ yet is spotted by James Webb Telescope

Subject: Science and tech

Section: Space sector

Context:

• A significant discovery by JWST includes observations of a galaxy that had ceased star formation when the universe was merely 5% of its current age.

Key Findings about the ‘dead galaxy’:

• Scientists announced that JWST had observed a galaxy that became ‘dead’ approximately 13.1 billion years ago, around 700 million years post-Big Bang.
• This marks it as the earliest dead galaxy found by about 500 million years.
• The study suggests the galaxy underwent a brief star formation burst lasting 30 to 90 million years before stopping. The reasons for this cessation are currently under investigation.
  • JWST’s advanced capabilities allow it to observe greater distances—and thus further back in time—than the Hubble Space Telescope. This has led to the discovery of the earliest-known galaxies, revealing them to be larger and more numerous than previously expected.
• Galaxy Characteristics:
  • This galaxy experienced a short, intense period of star formation before halting abruptly. With an estimated population of 100 million to one billion stars, the galaxy is considered relatively small.
  • After the halt in star formation, galaxies evolve into what can be likened to stellar graveyards. As stars die without replacement, the galaxy’s colour transitions from blue (indicative of hot, massive stars) to yellow, then red (indicative of less massive stars). The most massive stars, which live the shortest lives, die first in a hierarchical fashion based on stellar weight.
• Significance of the discovery:
  • The discovery is particularly intriguing given the active and violent state of the early universe, which had abundant gas to fuel star formation in galaxies. The abrupt cessation of star formation in such a galaxy poses a significant puzzle.
  • This discovery underscores JWST’s pivotal role in advancing our understanding of the universe’s early days, revealing phenomena that challenge current cosmological models and theories.