Part 3

 A star is an object in space made up of hot gases, with a core that is like a thermonuclear reactor.

 Forms from the materials in a nebula when gravity starts acting on chunks of gas and dust, pulling them together.

 As gravity keeps working, the mass grows and the material collapses in on itself and contracts.  An early phase of star, called a “protostar,”

 Low mass stars  these stars start small  exist that way for most of their life as dim, cool red dwarfs.  burn their hydrogen fuel very slowly 100 billion years.  Die as hot dim white dwarfs and quietly burn out.

 Intermediate mass stars ( the Sun)  star lasts only about 10 billion years.  long period of stability  expands into a red giant.  slowly shrinking into a small, dim white dwarf.  it cools into a black dwarf, a dense, dark body made up mostly of carbon and oxygen.

 High mass stars  12 or more times the mass of the Sun  consume their fuel faster than smaller stars  Become red giants. (supergiants)  last for only 7 billion years.  they collapse in on themselves causing a massive explosion called a supernova.  the remaining core of the supernova will eventually collapse to form a neutron star. A sphere only 10 km wide.

High mass stars

StarRelative Size Vega2.135 Canopus8.5 Sun1 Arcturus1.1 Betelgeuse18-19 Rigel17 Delta Orionis20