1.Science Daily Starter April 27, 2008

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• Daily Starters April 28-May 2

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2. Science Daily Starter April 27, 2008

What is the first stage in the life cycle of a star?

3. Life Cycle of a Star Ms. Hyche 1 st , 2 nd , 6 thperiod Science 4. Nebulae

Nebulae

• A nebulae is a cloud of gas and dust in outer space.

• These clouds are often very large, spanning across many light years.

• There are many different kind of nebulas in the sky

5. Nebulaes

Ring Nebulae

Double Lobed Nebulae

6. Other Nebulaes.

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7. Life Cycle of Stars

Just like people, stars are born, grow old, and eventually die.

The difference is, stars exist for billions of years.

8. How do stars form?

They are born when clouds of gas and dust come together and become very hot and dense. (nuclear fusion)

As stars get older, they lose some of their material.

Usually this is a gradual change, but sometimes it happens in a big explosion.

Either way, when a star dies, much of its material returns to space.

There some of it combines with more gas and dust to form new stars.

9. Types of Stars

Determinded by size, mass, brightness, color, temperature, specturm, and age

Main-sequence stars, giants, supergiants, white dwarfs

10. Main-Sequence Stars

Second and longest stage

Energy generated in the core, and released

Size changes very little as long as there is a continuous supply of hydrogen atoms to fuse the helium atoms

11. Giants and Supergiants

Third stage

Star can become ared giant

• A star that expands and cools once it uses its hydrogen

• Star will shrink

12. Scale 13. White Dwarfs

Final stage

Size of the sun or smaller

White Dwarf

• Small, hot star that is the leftover center of an older star

14. The Diagram That Did It!

In 1911, a Danish astronomer named Ejnar Hertzsprung compared the temperature and brightness of stars on a graph.

Two years later, American astronomer Henry Norris Russell made some similar graphs.

15. 16. 17. The Diagram That Did It

Although they used different data, they had similar results.

The combination of their ideas is now called the Hertzsprung-Russell, orH-R diagram .

• TheH-R diagramis a graph showing the relationship between a stars surface temperature and its absolute magnitude.

18. 19. 20. Continued

The H-R-diagram has become a tool for studying the nature of stars.

It shows how stars are classified by temperature and brightness AND its a good way to illustrate how stars change over time.

21. As stars age.

Average stars (sun), become red giants and then white dwarfs

More massive stars may explode with such intensity that they become strange objects such as supernovas, neutron stars, pulsars, and black holes

22. Supernovas

Massive blue stars with short lives

Supernova

• Gigantic explosion in which a massive star collapses.

23. Neutron Stars

Neutron star

• A star that has collapsed under gravity to the point that the electrons and protons have smashed together to form neutrons

Pulsar

• Spinning neutron star

24. 1987A 25. 1987A 26. Blackholes

Leftovers of a supernova that they collapse

Black hole

• Object so massive and dense that even light cant escape its gravity

27. 28. Life Cycles

The life cycle of a star varies, depending on the mass of the star.

Higher mass stars develop more quickly than lower mass stars. Toward the end of their life, they also behave differently.

29. More on life cycles

Stars form inside a cloud of gas and dust called a nebula.

Gravity pulls gas and dust closer together in some regions of a nebula.

As the matter contracts, it forms a hot, dense sphere.

The sphere becomes a star if the center grows hot and dense enough for fusion to occur.

30. 31. 32. 33. 34. 35. 36. 37. Death of a Star

When a star begins to run out of fuel, its core shrinks and its outer portion expands.

Depending on its mass the star becomes either a red giant or a supergiant.

These evolve in very different ways.

38. Low or Medium Mass Star

Low or medium mass star

• Red Giant

• Planetary Nebula

• White Dwarf

• Black Dwarf

39. High Mass Star

High Mass Star

• Supergiant

• Supernova

• Black hole (gravity so strong that nothing, not even light, can escape) or neutron star

40. In conclusion.

Nebulae

Main-Sequence Star

Giants or Red Giants

White Dwarfs

Supernovas, Neutrons, Blackholes

41. 42. 43. 44. 45. 46. 47.