Astronomers have recently discovered a young star in the violent and tortured environment around the supermassive black hole at the core of the Milky Way galaxy, known as Sagittarius A* (Sgr A*).


About Sagittarius A* (Sgr A*)

  • It is a supermassive black hole located at the centre of the Milky Way Galaxy.
  • It is located in the constellation Sagittarius.
  • It has a mass equivalent to four million Suns.
  • It has a diameter of around 5 million kilometres .
  • It is mostly dormant and only occasionally absorbs gas or dust.
  • The event horizon of the black hole has a radius of 12 million km.


What is a Black hole?

  • A black hole is a region in space where gravity pulls so much that even light can not get out.
  • The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.
  • Because no light can get out, it is difficult to detect a black hole.
  • The largest black holes are called “supermassive.” These black holes have masses that are more than 1 million suns together.
  • Albert Einstein first predicted the existence of black holes in 1916, with his general theory of relativity.


What is the ‘event horizon’ of a Black hole?

  • It is the boundary defining the region of space around a black hole from which nothing (not even light) can escape.
  • The escape velocity for an object within the event horizon exceeds the speed of light.
  • The radius of the event horizon is called the Schwarzschild radius, after the German astronomer Karl Schwarzschild.