Black Holes

• Black Holes


  Astronomical objects with a gravitational pull so strong that nothing, not even light, can escape it
• Black Holes


  • Their surface, or event horizon, defines the boundary where the velocity needed to escape exceeds the speed of light (the speed limit of the cosmos)
  • Not visible as they do not emit light but their presence is detectable by observing its effects on surrounding matter
• Formation of Black Holes

  1. Massive stars die and collapse on themselves

  2. When a large star runs out of fuel causing its core to crush inwards under its own gravity, creating a mass several times greater than the Sun's
• Types of Black Holes

  • Stellar-mass black holes
  • Supermassive black holes
  • Intermediate-mass black holes
• Stellar-mass black holes


  Formed by the collapse of massive stars with masses ranging from a few times the Sun's mass up to about 100 times the Sun's mass
• Supermassive black holes


  Enormous black holes with millions to billions of times the Sun's mass that is thought to reside at the center of most galaxies like the Milky Way
• Sagittarius A


  • Supermassive black hole at the center of the Milky Way; 4 million times the Sun's mass
• Cygnus X-1


  • Stellar-mass black hole in the constellation Cygnus; 14.8 times the Sun's mass
• M87

  • An elliptical galaxy with a black hole that was the first to be captured in a telescope; 6.5 billion times the Sun's mass