1 / 57

Questions

Questions. How do we form hypotheses about the formation of our Solar System? In what ways can we scientifically test ideas about the Solar System’s formation and e arly events? What is the Solar System’s destiny?. Building A Solar System. Step 1. Fuse Metals. Origin of Matter.

tareq
Télécharger la présentation

Questions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Questions • How do we form hypotheses about the formation of our Solar System? • In what ways can we scientifically test ideas about the Solar System’s formation and early events? • What is the Solar System’s destiny?

  2. Building A Solar System

  3. Step 1.Fuse Metals

  4. Origin of Matter • All matter originated at the Big Bang • Primordial nucleosynthesis • A few minutes after the big bang, protons were highly dense and very energetic, allowing fusion • For about 17 minutes, nucleosynthesis could occur

  5. Big Bang Nucleosynthesis • Discussed by Alpher-Bethe-Gamow in 1940s H + H  D • Nearly all deuterium originated in the big bang • Also formed 3He, 4He, 7Li • ~10:1 H:He ratio • Beyond that energy required wasn’t amenable

  6. T=1000 s

  7. Stars and fusion Lots of fusion http://webhome.idirect.com/~rsnow/aboutstars.htg/H-RDIAGRAM.gif Less fusion

  8. Nuclear Fusion • The process of forming a new atomic nucleus by the fusing of two or more nuclei • Hydrogen is “burned” to form Helium, and further fusion leads to other elements • Fusion only occurs at high temperatures (core of the Sun, nuclear bomb, early big bang) Coulombic Barrier + +

  9. H  He 2 H D 2 H 4He D + H 3He 2 3He

  10. Synthesis of heavier elements • Requires bigger, hotter stars • High temperature means more energy to overcome coulomb barrier • Also means more frequent collisions between nuclei, so short-lived nuclei can act as intermediates

  11. More Burning 16O • Triple alpha process 8Be 8Be 2 4He 12C 4He

  12. Origin of heavier elements http://www.hacastronomy.com/sn/onion_skin_model.gif

  13. From Stellar Nucleosynthesis

  14. Heavier elements • Require energy to synthesize • No pay for their own nucleosynthesis • Supernova • Form new elements by proton/neutron capture • Result in the periodic table http://magic.mppmu.mpg.de/snr.jpg

  15. Anders and Grevasse 1989

  16. Anders and Grevasse 1989 Most abundant elements easiest to synthesize

  17. Anders and Grevasse 1989 Heavy elements much rarer than light elements

  18. Anders and Grevasse 1989 Sawtooth pattern from addition of He nuclei

  19. Anders and Grevasse 1989 Iron peak- the dead end of nucleosynthesis

  20. Anders and Grevasse 1989 Easy to burn light elements so Li, Be, B are depleted

  21. Step 2.Destroy an old star

  22. Supernova 1987a • Brightest Explosion since Kepler’s time • Guess the year it happened! • Ring of expelled gas from earlier • Bipolar filaments

  23. Supernova 1987a • Brightest Explosion since Kepler’s time • Guess the year it happened! • Ring of expelled gas from earlier • Bipolar filaments • Hubble has been watching… http://hubblesite.org/newscenter/archive/releases/2004/09/

  24. Planetary Nebula • Not actually planetary at all: Herschel thought they looked like planets, that they were new planetary systems forming.

  25. Nebula • Orion Nebula • ~2000 Solar Masses

  26. Step 3.Condense a New Star

  27. Young Stars • Material condenses from “small” shock waves, perturbations in nebula • Spinning increases (Moment of Inertia) • Fusion begins when P/T is achieved • Materials fall into new star and are ejected • This modifies the solar system!

  28. Step 4.Get a Proplyd

  29. (Pro)to(Pl)anetar(y D)isk = Proplyd • Material spins out like record, Earth • North and South of Sun, material is excavated by jets • Orion Nebula proplyds

  30. Step 5.Build Particles

  31. Anders and Grevasse 1989 Take a gas of this composition and cool it. What forms?

  32. First thing to form: • Ceramics • These are high temperature minerals • First condensates

  33. Called Calcium-Aluminum rich inclusions

  34. Then come silicates and metal • Olivine and iron

  35. Silicates melted • Formed chondrules

  36. Volatile materials • Phosphorus • Lower temeprature silicates (Na-, K-bearing) • Sulfides • Ices Where do they go?

  37. Step 6.Build Masses

  38. Earth formed from Solar System debris • Earth and other planets form from a mixture of rocky material • Meteorites • Asteroids • Comets Hoba- www.nmm.ac.uk

  39. Origins of the Earth’s constituents • Volatile components, including key biogenic elements, were in short supply on the early Earth • Earth was hot • Volatiles were lost or were not delivered • Not primordial (20Ne, 36Ar)

  40. Loss of volatiles on inner planets P H, C, N, O

  41. Delivery of Volatiles to the Earth Cometary Delivery Late Veneer • Carbonaceous Chondrites, with hydrated minerals, were the last accreted constituent to the early earth • Outgassing of volatiles led to hydro + atmosphere • Consistent with D/H ratio • Something odd going on with PGEs • Comets, loaded with H2O and organics, were the source of volatiles • Loaded with water • High flux (possibly) to early Earth • D/H ratio is much higher than earth • What were early comets really like?

  42. Step 7.“Crush The Masses” -Stalin

  43. Planetary accretion • Dust grains and small particles collide and stick together • Accumulate, making larger and larger bodies • A miracle occurs • Planets form http://ircamera.as.arizona.edu/NatSci102/NatSci102/images/accretion.jpg http://blog.stackoverflow.com/wp-content/uploads/then-a-miracle-occurs-cartoon.png

  44. Step 8.Differentiate the Planets

  45. Processing of planets • Planets accreted and were warmed • Radioactive decay of short-lived elements? • Impact heating • Warming causes differentiation of planets

  46. Step 9.Rearrange and Watch Out

More Related