1. Lives of Stars

2. lifetimes of stars how long a star lives depends on its mass
greater the mass- shorter the lifetime

3. star’s life cycle

4. nebula= large cloud of gas & dust
birthplace of stars

5. Image by NASA/STSCI/Nolan Walborn/Hubble Heritage Team
nebula
Image by NASA/STSCI/Nolan Walborn/Hubble Heritage Team

7. 1. protostar Earliest stage in star’s life
Contracting cloud of gas & dust w/ enough mass to make star

9. 2. main sequence star (developed star)
sun

10. start to run out of fuel- outer layers expand
3. red giant or supergiant
start to run out of fuel- outer layers expand

12. depends on star ’s mass When star runs out of fuel, becomes :
white dwarf or
neutron star or
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. when white dwarf stops glowing
5. black dwarf-
when white dwarf stops glowing

16. giant & supergiant stars
4. supernova- explosion of a dying giant or supergiant 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

21. 5. black hole- most massive stars
form from stars that have 40 times the 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 artist’s impression shows a black hole pulling matter from a companion star.

23. Not even light can escape from a black hole.

24. (unsequenced human life cycle page)
supernova
nebula
developed star
black hole
protostar
supergiant
(unsequenced human life cycle page)

25. protostar
nebula
protostar
protostar

26. Life Cycle of a Star nebula= huge cloud of gas & dust
protostar= beginning of star
Life Cycle of a Star
developed star (main sequence star)
red giant or supergiant= star expands, outer layers cool
low mass star
massive star
white dwarf= dim star that forms from a red giant
supernova= enormous explosion of a giant star
very high mass
high mass star
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 star’s core