CHAPTER 12 OUTSIDE OUR SOLAR SYSTEM.

Part 3

The Formation of Stars

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

The Formation of Stars

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

The Formation of Stars

As gravity keeps working, the mass grows and the material collapses in on itself and contracts.

An early phase of star, called a “protostar,”

Life Cycle of a Star 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.

Life Cycle of a Star 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.

Life Cycle of a Star 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.

Life Cycle of a StarHigh mass stars

Common stars and the Sun

Star Relative Size

Vega 2.135

Canopus 8.5

Sun 1

Arcturus 1.1

Betelgeuse 18-19

Rigel 17

Delta Orionis 20