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Cosmic Fireworks: Supernova Explosions

Cosmic Fireworks: Supernova Explosions. Stephen C.-Y. Ng McGill University. Outline. Why study supernova? What is a supernova? Why does it explode? The aftermaths --- Supernova remnants Will it destroy the Earth?. Where do they come from?. Mines?. Supernova Explosions!.

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Cosmic Fireworks: Supernova Explosions

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  1. Cosmic Fireworks:Supernova Explosions Stephen C.-Y. Ng McGill University

  2. Outline • Why study supernova? • What is a supernova? • Why does it explode? • The aftermaths --- Supernova remnants • Will it destroy the Earth?

  3. Where do they come from?

  4. Mines?

  5. Supernova Explosions!

  6. Gold, Silver & More

  7. Heavy Elements

  8. Building Blocks of Life

  9. Life from Exploding Stars! Without supernovae to disperse elements made in stars, no planets, no life!!

  10. Why Study Supernova? • They are cool • most powerful explosions in the Universe 1,000,000,000,000,000,000,000,000,000 = 1044J 1017J

  11. Why Study Supernova? • They are cool • most powerful explosions in the Universe • They are important • produce heavy elements beyond iron, e.g. gold, silver,… • recycle materials into space, e.g carbon, oxygen,… • shock wave triggers new star formation • They can get you a Nobel prize • SN Type Ia as standard candles for cosmology • They are bombs • shock wave physics

  12. What is a Supernova? • Nova= new star • Death of a star, most powerful explosions: • 1027 nuclear bombs • brighter than a galaxy (~1011 stars) • more energy than the entire lifetime of a star SN 1994D • Naming: • SN 2012A, …, SN2012Z, SN 2012aa,…SN 2012ab, …, SN 2012gh

  13. Historical Classification SN H no H Si no Si no He He Type Ia Type Ib Type Ic Type II

  14. Physical Classification SN H no H Si no Si no He He Type Ia Type Ib Type Ic Type II Thermonuclear Core Collapse

  15. Why do they explode? • Stellar evolution • Core collapse • Thermonuclear

  16. Life of a Sun-like Star Sun-like Star Protostars Red Giant Star-Forming Nebula Planetary Nebula White Dwarf

  17. Life of a Massive Star Massive Star Protostars Red Supergiant Star-Forming Nebula SUPERNOVA Neutron Star Black Hole

  18. Pressure Balance 2,000,000,000x in 1 second! self gravity gas pressure

  19. Stellar Alchemy

  20. Life of a Sun-like Star Sun-like Star Protostars Red Giant Star-Forming Nebula Planetary Nebula White Dwarf

  21. Massive Stars

  22. Stellar Onion

  23. Inert Iron Core

  24. Stellar Onion not to scale

  25. Core Collapse self gravity gas pressure

  26. Core Bounce nuclear force

  27. Core Bounce triggers new star formation produce heavy elements energy: 1046J99% neutrinos 1% kinetic energy 0.01% visible light recycle light elements

  28. Compact Core

  29. How about SN Type Ia?

  30. Main Ingredient: White Dwarf White Dwarf

  31. Mass Transfer

  32. Accreting White Dwarf

  33. Binary Merger

  34. Standard Candles

  35. When can I see a Supernova? • Expect 1–2/century in our Galaxy, but long overdue: • G1.9+0.3 (~1868AD): • not visible on Earth, toofar and obscured • Cassiopeia A (~1680AD):peak magnitude = 6?too faint to see

  36. SN 1054 • 1054AD July 4 • Crab Nebula (Messier 1)

  37. Crab Nebula • Remnant of SN1054 • Harbors the Crab Pulsar --- most energetic neutron star found in the Milky Way

  38. Historical Supernovae • SN 1006 • 1006AD May 1 • brightest SN observed • visible for ~18months • Tycho’s SN • 1572AD November • as bright as Venus • visible until 1574 • Kepler’s SN • 1604AD October 9 • visible in day time for 3 weeks

  39. Can I See One Now? • Catch one in the act? Go extragalactic! • As of today, 6065 extragalactic SNe observed

  40. Extragalactic SNe SN 1994D in NGC 4526 SN 2004et in NGC 6946

  41. SN 1987A

  42. SN 1987A • 1987 Feb 23, in the Large Magellanic Cloud • closest (hence brightest) SN observed in 300 yr, since invention of modern telescope • ~11 neutrinos detected, 3 hr prior to visible light • complex environment Milky Way LMC 168,000 light year SMC

  43. Observations Optical X-ray Radio Chandra X-ray Observatory Australia Telescope Compact Array

  44. Evolution

  45. Expansion 4000 km/s 35,000 km/s

  46. Next Supernova in the Milky Way • A major event will be observed by every telescopes in all wavelengths • radio, IR, optical, X-ray, -ray,... • Multimessenger astronomy beyond EM radiation • neutrino telescopes • gravitational wave detectors

  47. location of our solar system Will it destroy the Earth? Nearest candidate (IK Pegasi): over 150 light years away! ~100,000 light years across • Supernova: within 30 light years Artist’s Conception of our Milky Way Galaxy

  48. Summary • Supernovae are important: • produce everything on Earth • Explosion mechanisms: • core collapse of massive stars • thermonuclear detonations of white dwarfs • The next supernova? • we are safe

  49. SNR G292.2-0.5

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