What do you think of when you look at the night sky?

1. What do you think of when you look at the night sky? http://www.astro.ufl.edu/~lada/ast3018/lectures/ast3018lecturestarform.pdf

2. What is Space? • Not really empty • Stars, planets, etc. • Interstellar medium • Dust and Gas • Nebulas Orion Nebula http://hubblesite.org/gallery/album/nebula/pr1995044a/ Large Magellanic Cloud http://hubblesite.org/gallery/album/nebula/pr2006055a/

3. Nebular Hypothesis • Random collisions of atoms • Areas of growing mass • Spherical shape • Pull in more matter • Increase in • Temperature • Pressure • Spin • Creates a bulge in the sphere http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap06/FG06_17.jpg

4. Nuclear Fusion • High temperatures • 2 particles become 1 • Releases a lot of energy • Video clip • Particle accelerators • Man-made • Create new elements • Find smallest particles http://www.universetoday.com/52696/nuclear-fusion-power-closer-to-reality-say-two-separate-teams/ Fermi National Lab http://www.wired.com/playbook/2012/08/olympics-physics-hammer-throw/

5. Spectroscopy Activity • Draw the lines that you see • Make sure the # of lines, color of the lines and order is accurate • Write a conclusion – based on your observations what can you conclude about the different materials and light you see the material produce

6. Warm Up #1 • Clicker Quiz • Compare conclusions from the spectroscopy activity

7. What does a spectrum tell us? • Each chemical/atom has a unique spectrum • Like a fingerprint • What chemicals are present http://www.umsl.edu/~physics/Lab%20Connection/Electricity%20and%20Magnetism%20Lab/12-lab13.html

8. How is a spectrum created? • All objects emit light • Pure light from a source • Continuous spectrum • If light passes through gas or dust • Light absorbed • Excites/heats atoms • Emit own light • Makes an emission spectrum • Unique https://www.cfa.harvard.edu/~jbattat/a35/cont_abs_em.html

9. How do astronomers use spectra? • Look at light from • Stars (gas in outer layers) • Nebula • Planets • Determine chemical composition • Can also determine movement of object • Activity http://www.eso.org/public/outreach/eduoff/cas/cas2004/casreports-2004/rep-236/

10. Warm Up #2 • Why are emission spectra important? • How are emission spectrum created? • What 2 things can astronomers learn by looking at the spectrum from a star?

11. H-R Diagram Graphing Activity • Look for patterns http://www.rootstown.sparcc.org/mattjust/h-r-diagram

12. Color and Temperature • What did you see as a pattern? • Objects give off a variety of light • Peak depends on temperature • Peak shows most common type of light http://docs.kde.org/stable/en/kdeedu/kstars/ai-colorandtemp.html

13. Main Sequence Stars • Find group on H-R diagram • Wide variety • Highest # of stars • Stars stay here the longest • Actively fusing hydrogen into helium • Outward pressure from fusion • Inward pressure from gravity • Equal in these stars • Maintain size http://www.thenakedscientists.com/HTML/articles/article/the-science-of-the-supernova/ http://www.rootstown.sparcc.org/mattjust/h-r-diagram

14. What happens to our Sun? • Form red giants • Fusing helium • Core collapsing • Outer layers spread out • Cools http://flightline.highline.edu/iglozman/classes/astronotes/media/2paths.jpg http://www.physics.uc.edu/~hanson/ASTRO/LECTURENOTES/StarLife/Page7.html

15. What then? • Forms a white dwarf • Ran out of helium • No more fusion • Outer gasses moving away • Planetary nebula • Leaves a hot, dense core http://chandra.harvard.edu/xray_sources/white_dwarfs.html Ring Nebula http://hubblesite.org/gallery/album/nebula/planetary/pr2004032d/ Cat’s Eye Nebula http://hubblesite.org/gallery/album/nebula/planetary/pr2004027a/

16. Warm Up #3 • What makes a star a main sequence star? • Why does the size of the core of a main sequence star not change? • What will eventually happen to our Sun and why?

17. What about the fate of larger stars? • Become red supergiants • Fuse elements larger than helium • All the way to iron • Short lives • Supernova • No more fusion • Core violently explodes • Fuses heavier atoms • Very bright, short time • Spreads out material http://flightline.highline.edu/iglozman/classes/astronotes/media/2paths.jpg http://hubblesite.org/gallery/album/nebula/supernova_remnant/pr2005037a/

18. What then? • Forms a neutron star • If a lower mass core • Very dense • Not very big • Lots of gravity • Can produce gamma and x-rays when it pulls items into it Neutron star in supernova Cassiopeia A http://www.space-pictures.com/view/pictures-of-space/pictures-of-stars/neutron-star/index.php http://www.clccharter.org/maya1/Supernova/supernova.html

19. Or… • Forms a black hole • Higher mass cores • Infinitely dense • Need to travel faster than the speed of light to escape • How can we see? • Will bend light from nearby stars • See dust and gas swirling around • Hot enough to give off x-rays • Probably at the center of most galaxies • Including ours! • Video http://www.space.com/15421-black-holes-facts-formation-discovery-sdcmp.html Whirlpool Galaxy http://hubblesite.org/gallery/album/pr2001010a/

20. Warm Up #4 • What is happening inside a red supergiant star? • What happens in a supernova? • How is a neutron star different from a black hole? • Why should we not be able to see a black hole? • Why can we “see” a black hole?