Life Cycle of a Life Cycle of a StarStar

NebulaNebula

11stst Stage of Life Stage of Life Ball of gas and dust that is pulled Ball of gas and dust that is pulled

together by gravitytogether by gravity Nuclear fusion starts as gas cloud Nuclear fusion starts as gas cloud

becomes denser and hotterbecomes denser and hotter Nuclear FusionNuclear Fusion hydrogen atoms fuse hydrogen atoms fuse

into heliuminto helium Creates the intense energy found in Creates the intense energy found in

starsstars

ProtostarProtostar

As a nebula collapses and As a nebula collapses and gravitational forces and rotation gravitational forces and rotation factor in a nebula will condense factor in a nebula will condense in the center.in the center.

Eventually the amassed heat Eventually the amassed heat becomes enough to start nuclear becomes enough to start nuclear fusion.fusion.

Four types of stars make Four types of stars make up the life of a starup the life of a starMain SequenceMain SequenceGiants Giants Super GiantsSuper GiantsWhite DwarfsWhite Dwarfs

Main Sequence (the Sun)Main Sequence (the Sun)22ndnd stage stageLongest stageLongest stageHydrogen changes into helium Hydrogen changes into helium which creates enormous amounts which creates enormous amounts of energyof energy

The size of the star does not The size of the star does not change muchchange much

Giants and SupergiantsGiants and Supergiants33rdrd stage stageMain Sequence star becomes a Main Sequence star becomes a

red giantred giant Red giantRed giant star that expands and star that expands and

cools once is loses all its hydrogencools once is loses all its hydrogenCenter shrinks and atmosphere Center shrinks and atmosphere

grows large and coolsgrows large and cools

White Dwarf White Dwarf small hot small hot star that is the leftover star that is the leftover center of an older starcenter of an older starFinal stageFinal stageCan shine for billions of Can shine for billions of years before they years before they extinguishextinguish

Hertzprung-Russell DiagramHertzprung-Russell DiagramShows the relationship between Shows the relationship between a star’s surface temperature and a star’s surface temperature and absolute magnitudeabsolute magnitude

Used to study the lives of starsUsed to study the lives of starsMost stars lie along the main Most stars lie along the main sequence portion of the diagramsequence portion of the diagram

Age of starsAge of starsAverage stars become red Average stars become red giants then white dwarfsgiants then white dwarfs

More massive stars More massive stars explode into a variety of explode into a variety of objectsobjects

SupernovaSupernova gigantic explosion in which gigantic explosion in which a massive star collapses a massive star collapses Occurs after a massive star uses up its Occurs after a massive star uses up its

fuel sourcefuel source Neutron StarNeutron Star a star that has collapsed a star that has collapsed

to a point at which all particles are to a point at which all particles are neutronsneutrons A neutron star that spins and sends out A neutron star that spins and sends out

beams of radiation is called a pulsarbeams of radiation is called a pulsar

Black HoleBlack Hole an object that is an object that is so massive that light cannot so massive that light cannot escape its gravityescape its gravityRemnants of a supernovaRemnants of a supernovaAstronomers can detect Astronomers can detect black holes by using X-ray black holes by using X-ray telescopestelescopes

Question 1Question 1

What kind of a star is What kind of a star is the sun?the sun?

AnswerAnswer

Main SequenceMain Sequence

Question 2Question 2

What is the H-R What is the H-R diagram?diagram?

AnswerAnswer

A graph that shows A graph that shows the relationship the relationship between a star’s between a star’s temperature and temperature and absolute magnitudeabsolute magnitude

Question 3Question 3

What are the four What are the four main types of stars?main types of stars?

AnswerAnswer

Main-SequenceMain-SequenceGiants and Giants and SupergiantsSupergiants

White DwarfsWhite Dwarfs