Life Cycle of Stars

1. Life Cycle of Stars

2. Life Cycle of Stars What is a star? • A ball of gas that makes light. • A luminous celestial body, made up of plasma, forming a sphere. • The Sun is one of billions of stars in the Milky Way galaxy.

3. Star Birth

4. Star Birth Dust and Gas • DUST and GAS • Come closer together due to gravity. • Mostly Hydrogen and Helium. Star Cluster N81

5. Star Birth Dust and Gas Gravity Protostar • PROTOSTAR • Gas condenses due to gravity. • Planets may form. • Temperature increases.

6. Star Birth Dust and Gas Gravity Protostar At a distance of 7000 light years this nebula contains the largest protostar yet to be discovered. This protostar is 300 times the size of our own solar system. A protostar is a gas cloud that "shrinks" its way to becoming a star.

7. Star Birth H + H = He + ENERGY • FUSION • Hydrogen molecules smash together to form Helium and energy. • Star begins to shine. • Bigger the star the faster it “burns”.

8. Star Birth Dust and Gas Gravity Fusion Protostar • FUSION • Hydrogen molecules smash together to form Helium and energy. • Star begins to shine. • Bigger the star the faster it “burns”.

9. Star Birth Main Sequence Star Dust and Gas Gravity Fusion Protostar • MAIN SEQUENCE STAR • Type of Main Sequence star depends on initial mass. • Bigger = Higher Temperature = Change in color.

10. Star Birth Blue Giants • MAIN SEQUENCE STAR • Type of Main Sequence star depends on initial mass. • Bigger = Higher Temperature = Change in color. Sun Class Red Dwarfs

11. Main Sequence Star Dust and Gas Gravity Fusion Protostar Blue Giants Sun Class Red Dwarfs

12. Star Birth Small Star Death

13. Small Star Death Small MSS Fuel used up • SMALL MAIN SEQUENCE STAR • Star uses all of its Hydrogen. It runs out of fuel. • Star cools and expands.

14. Small Star Death Small MSS Red Giant Fuel used up • RED GIANT • Hydrogen is used up. • Star expands and cools. • Really big.

15. Small Star Death Core Collapse Small MSS Fuel used up Red Giant • PLANETARY NEBULA • Core condenses due to gravity. • Outer gasses expand outward.

16. Small Star Death Core Collapse Small MSS Planetary nebula Fuel used up Red Giant • PLANETARY NEBULA • Core condenses due to gravity. • Outer gasses expand outward. Spirograph Nebula

17. Small Star Death Eight Burst Nebula

18. Small Star Death Little Ghost Nebula

19. Small Star Death Helix Nebula A mere seven hundred light years from Earth, in the constellation Aquarius, a sun-like star is dying. Its last few thousand years have produced the Helix Nebula (NGC 7293), a well studied and nearby example of a Planetary Nebula, typical of this final phase of stellar evolution. Nearly 11 hours of exposure time have gone into creating this remarkably deep view of the nebula. It shows details of the Helix's brighter inner region, about 3 light-years across, but also follows fainter outer halo features that give the nebula a span of well over six light-years. The white dot at the Helix's center is this Planetary Nebula's hot, central star.

20. Small Star Death Core Collapse Small MSS Planetary nebula White Dwarf Fuel used up Red Giant • WHITE DWARF • Outer nebula expands away. • Small dense core remains. • Size of the Earth, but the mass of the Sun. • Will eventually burn out and become a Black Dwarf.

22. Star Birth Small Star Death Large Star Death

23. Large Star Death Large MSS Large MSS To be large a star must be 4-5 times more massive than out Sun. A good example is Rigel in the Orion constellation. It is as bright as 70,000 Suns.

24. Large Star Death Large MSS To be large a star must be 7 times more massive than out Sun. A good example is Rigel in the Orion constellation. Rigel

25. Large Star Death Large MSS Supergiant Fuel used up • SUPER GIANT • Hydrogen is used up. • Star expands and cools. • Really big.

27. Large Star Death Large MSS Blow up Supernova Supergiant Fuel used up Supernova Remnant • SUPERNOVA • Explosion of outer gasses. • Very quick. • Collapse of core.

28. Large Star Death Large MSS Blow up Supernova Supergiant Fuel used up Crab Nebula • SUPERNOVA • Explosion of outer gasses. • Very quick. • Collapse of core.

29. Star Collapse H + H = He + ENERGY • STAR COLLAPSE • Outward force of fusion is gone. • Gravity dominates.

30. Large Star Death NeutronStar Supernova A neutron star is about 12 miles in diameter and has the mass of about 1.4 times that of our Sun. This means that a neutron star is so dense that on Earth, one teaspoonful would weigh a billion tons! Because of its small size and high density, a neutron star possesses a surface gravitational field about 200,000,000,000 times that of Earth.

31. Large Star Death NeutronStar Supernova Pulsating Neutron Star = Pulsar • NEUTRON STAR • Collapse of core. • Very dense.

32. Large Star Death NeutronStar Supernova Black Hole • BLACK HOLE • Complete collapse of the core. • Infinitely small. Infinitely dense. Center of Milky Way

33. Large Star Death NeutronStar Supernova Black Hole

36. The sun is a mass of incandescent gasA gigantic nuclear furnaceWhere hydrogen is built into heliumAt a temperature of millions of degreesYo ho, it's hot, the sun is notA place where we could liveBut here on Earth there'd be no lifeWithout the light it givesWe need its lightWe need its heatWe need its energyWithout the sun, without a doubtThere'd be no you and meThe sun is a mass of incandescent gasA gigantic nuclear furnaceWhere hydrogen is built into heliumAt a temperature of millions of degreesThe sun is hotIt is so hot that everything on it is a gas: iron, copper, aluminum, and many others.The sun is large If the sun were hollow, a million Earths could fit inside. And yet, the sun is only a middle-sized star.The sun is far awayAbout 93 million miles away, and that's why it looks so small.And even when it's out of sightThe sun shines night and dayThe sun gives heatThe sun gives lightThe sunlight that we seeThe sunlight comes from our own sun'sAtomic energyScientists have found that the sun is a huge atom-smashing machine. The heat and light of the sun come from the nuclear reactions of hydrogen, carbon, nitrogen, and helium. The sun is a mass of incandescent gasA gigantic nuclear furnaceWhere hydrogen is built into heliumAt a temperature of millions of degrees

37. Life Cycle of Stars