1.Sec. 3 Lives of Stars

2. lifetimes of stars

how long a star lives depends on its mass

greater the mass- shorter the lifetime

3. stars life cycle 4.

nebula = large cloud of gas & dust

birthplace of stars

5. Image by NASA/STSCI/Nolan Walborn/Hubble Heritage Team nebula 6. 7. 1.protostar

Earliest stage in stars life

Contracting cloud of gas & dust w/ enough mass to make star

8. 9. sun 2.main sequence star(developed star) 10. 3.red giant or supergiant start to run out of fuel- outer layers expand 11. 12.

When star runs out of fuel, becomes :

white dwarfor

neutron staror

black hole

depends on star s mass 13. small & medium stars become

white dwarf-

• • • • cooled blue-white core left behind

• • • • about size of Earth

same mass as Sun

14. This Hubble Space Telescope image shows Sirius A, the brightest star in our nighttime sky, along with its faint, tiny stellar companion, Sirius B.Astronomers overexposed the image of Sirius A [at center]so that the dim Sirius B [tiny dot at lower left] could be seen. 15.

5. black dwarf-

when white dwarf stops glowing

16.

giant & supergiant stars

4.supernova - explosion of a dying giant orsupergiant star

one of the most dazzling events in the universe

17. supernova 18.

5.neutron star-small, dense star

• • • • - 3 X mass of Sun

19. pulsar

Spinning neutron star

Emits pulses of radio waves

20. 21.

5. black hole-most massive stars

• • • form from stars that have 40 timesthe mass of sun

• • • gravity is so strong that nothing can escape- not even light

• • • x-rays detect them

22. The remains of the most massive stars collapse into black holes.This artists impression shows a black hole pulling matter from a companion star. 23. Not even light can escape from a black hole. 24. ( unsequencedhuman life cycle page ) nebula protostar developed star supergiant supernova black hole 25. nebula protostar protostar protostar 26. Life Cycle of a Star nebula =huge cloud of gas & dust protostar = beginning of star red giant or supergiant = star expands, outer layers cool supernova = enormous explosion of a giant star white dwarf = dim star that forms from a red giant black dwarf = runs out of fuel dead star black hole =core collapses to a tiny point with a very strong gravitational pull neutron star = dense remains of a massive stars core low mass star high mass star very high mass massive star developed star (main sequence star)