Neutron Stars and Back Holes

                           Neutron Star

                               Black Hole 

           Neutron Stars and Black Holes

Neutron Stars and Back Holes are formed after the Supernova explosion of the Stars. If the remaining core is less than three solar masses contraces to form Neutron Star. If the remaining core is greater than three solar masses it contraces so form a Black Hole. Neutron Stars contain subatomic particles called neutrons weighing about a billion tonnes. They restane rapidly amitting two beams of radio wares. The gravitation of the black holes is so extremely strong that not even light or radiation waves can escape from the As the gravitation is strong gases from other Stars are pulled in by the Black Hole. The gas accumulates to form a spiraling disc around the Black Hole. The dac spirals at a high speed and heats up sending out radiation. The spiralling of the disc to cross the boundary of the black hole makes it invisible to the visible Universe.

                             Stars

Age: Between 1 million and 15 years 
Mars: From 1/20 to 100 times the mass of the sun.
Temperature: Surface: 2800° C to 28000° C Centre: more than 1,100,000° C 
Diameter: Largest stars- about 1.6 billion kilometres.
Smallest stars- about 20 kilometres Composition: 75% hydrogen 22% helium,
and traces of other elements.
Brightest star (excluding sun): Sisus 
Nearest star to the earth (excluding sun): Proxima Centauri (4.3 light years from the earth)