International Space Agencies – Missions and Discoveries

Accretion Disc of a Black Hole


From UPSC perspective, the following things are important :

Prelims level : Accretion Disc of a Black Hole

Mains level : Black-hole theory and its relevance

  • A new visualization of a black hole, released by NASA, illustrates how its gravity distorts our view by warping its surroundings.

Accretion Disc

  • The black hole’s extreme gravity skews light emitted by different regions of the disc, producing the misshapen appearance.
  • This visualization simulates the appearance of a black hole where infalling matter has collected into a thin, hot structure called an accretion disc.
  • As magnetic fields twist through the churning gas, bright knots form and dissipate in the disc.
  • In the area closest to the black hole, the gas orbits at close to the speed of light.
  • The outer portions spin a bit more slowly.
  • This difference stretches and shears the bright knots, producing light and dark lanes in the disk.

How it is formed?

  • The black hole’s extreme gravity alters the paths of light coming from different parts of the disc, producing the warped image.
  • Exactly what we see depends on our viewing angle; the greatest distortion occurs when viewing the system nearly edgewise.
  • Glowing gas on the left side moves toward us so fast that the effects of Einstein’s relativity give it a boost in brightness.
  • On the right side, gas moving away becomes slightly dimmer.
  • This asymmetry disappears when we see the disc exactly face on because, from that perspective, none of the material is moving along our line of sight.


Black Hole

  • A black hole is an object in space that is so dense and has such strong gravity that no matter or light can escape its pull. Because no light can escape, it is black and invisible.
  • They drastically warp the fabric of space-time and anything that passes too close gets sucked into it be it a wandering star or a photon of light.
  • They exist from the size of a human cell to more massive than the sun.
  • Black holes of stellar mass are formed when a massive star collapses at the end of its life cycle.
  • After a black hole forms, it continues to grow by absorbing mass from its surroundings.
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