Why in the news?

  • Astronomers have unearthed evidence that some  of the earliest luminous objects in the universe may be “dark stars” by using James Webb Space
 Telescope.

James Webb Space Telescope (JWST)

  • Launch: 2021
  • Launch Vehicle: Ariane-5 rocket (from French Guiana).
  • Orbit: Second Lagrange Point (L2), about 1.5 million km from Earth- a stable point for deep-space observation.
  • Space Agencies Involved: It is a joint collaboration between NASA (USA), ESA (European Space Agency), and CSA (Canadian Space Agency).
  • Objectives:
    • Study Early Universe: Observe the first galaxies and stars formed after the Big Bang (~13.5 billion years ago).
    • Exoplanet Exploration: Analyse atmospheres of exoplanets to detect signs of habitability and potential biosignatures.
    • Star and Planet Formation: Investigate birth of stars and formation of planetary systems from interstellar dust.
    • Infrared Astronomy: Detect light from distant, faint, and cool objects invisible to optical telescopes.
  • Major Discoveries:
    • Detected galaxies formed just 320 million years after the Big Bang- the earliest known.
    • Found complex organic molecules in interstellar space.
    • Captured detailed spectra of exoplanets like WASP-39b showing atmospheric chemistry.
    • Observed stellar nurseries like the Carina Nebula and Pillars of Creation in unprecedented detail.
    • Provided insights into dark matter distribution and galactic evolution.

Dark Star

  • Proposed by Katherine Freese and colleagues (University of Michigan) in 2007.
  • These stars are powered by dark matter annihilation energy rather than nuclear fusion.
  • Instead of burning hydrogen like normal stars, they convert dark matter particles (e.g., WIMPs – Weakly Interacting Massive Particles) into radiation, which prevents collapse and keeps the star stable.
  • They could grow up to millions of times the mass of the Sun, making them supermassive and extremely luminous in infrared wavelengths- consistent with JWST observations.