Cosmic Fireworks: Supernova Explosions
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The document discusses supernovae and their importance. It explains that supernovae are either caused by the core collapse of massive stars or the thermonuclear detonation of white dwarfs. Supernovae are crucial because they produce heavy elements, disperse materials to form new stars, and could provide clues about the early universe. The next supernova in our galaxy would be a major multi-messenger event observed across the electromagnetic spectrum and other messengers like neutrinos and gravitational waves. However, the nearest candidate star is over 150 light years away so the earth is safe from being destroyed by a nearby supernova explosion.
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Cosmic Fireworks: Supernova Explosions
- 1. Dr. Stephen C. Y. Ng Department of Physics 超新星
- 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?
- 7. Gold, Silver & More
- 9. Building Blocks of Life
- 10. Life from Exploding Stars! Without supernovae to disperse elements made in stars, no planets, no life!!
- 11. Why Study Supernova? They are cool most powerful explosions in the Universe 1017J 1044J1,000,000,000,000,000,000,000,000,000 =
- 12. Why Study Supernova? 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 They are cool most powerful explosions in the Universe
- 13. What is a Supernova? Nova 新星 = new star Supernova 超新星 Naming: SN 2013A,…, SN2013Z, SN 2013aa,… SN 2013ab,…, SN 2013ej,… Death of a star, most powerful explosion: 1027 nuclear bombs brighter than a galaxy (~1011 stars) more energy than the entire lifetime of a star SN 1994D
- 14. Historical Classification SN no H H Si no Si He no He Type Ia Type Ib Type Ic Type II
- 15. Physical Classification Thermonuclear Core Collapse SN no H H Si no Si He no He Type Ia Type Ib Type Ic Type II
- 16. Why do they explode? Stellar evolution Core collapse Thermonuclear
- 17. Life of a Sun-like Star Protostars White Dwarf Planetary Nebula Red Giant Sun-like Star Star-Forming Nebula
- 18. Life of a Massive Star Protostars Black Hole SUPERNOVA Red Supergiant Massive Star Star-Forming Nebula Neutron Star
- 22. Stellar Alchemy
- 23. Life of a Sun-like Star Protostars White Dwarf Planetary Nebula Red Giant Sun-like Star Star-Forming Nebula
- 24. Massive Stars
- 25. Stellar Onion
- 26. Inert Iron Core
- 27. Stellar Onion not to scale
- 30. Core Bounce energy: 1046J 99% neutrinos 1% kinetic energy 0.01% visible light produce heavy elements recycle light elements triggers new star formation
- 31. Compact Core
- 33. Physical Classification Thermonuclear Core Collapse SN no H H Si no Si He no He Type Ia Type Ib Type Ic Type II
- 34. How about SN Type Ia?
- 35. White Dwarf Main Ingredient: White Dwarf
- 36. Mass Transfer
- 39. Standard Candles
- 40. Standard Candles
- 41. When can I see a Supernova? • Expect 1–2/century in our Galaxy, but long overdue: Cassiopeia A (~1680AD): peak magnitude = 6? too faint to see G1.9+0.3 (~1868AD): not visible on Earth, too far and obscured
- 42. SN 1054 • 1054AD July 4 • Crab Nebula (Messier 1)
- 43. Crab Nebula • Remnant of SN1054 • Harbors the Crab Pulsar --- most energetic neutron star found in the Milky Way
- 44. Historical Supernovae Tycho’s SN •1572AD November •as bright as Venus •visible until 1574 SN 1006 •1006AD May 1 •brightest SN observed •visible for ~18months Kepler’s SN •1604AD October 9 •visible in day time for 3 weeks
- 45. Can I See One Now? • Catch one in the act? Go extragalactic! • As of today, 6000+ extragalactic SNe observed
- 46. Extragalactic SNe SN 2004et in NGC 6946SN 1994D in NGC 4526
- 47. SN 2013ej in M74 Taken here in HKU
- 48. SN 1987A
- 49. 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 SMC
- 50. Observations Australia Telescope Compact Array Chandra X-ray Observatory Optical X-ray Radio
- 51. Evolution
- 53. Next Supernova in Our Galaxy 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
- 54. ~100,000 light years across Artist’s Conception of our Milky Way Galaxy Will it destroy the Earth? location of our solar system Nearest candidate (IK Pegasi): over 150 light years away! Supernova: within 30 light years
- 55. 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
- 56. SNR G292.2-0.5
- 58. Triple Ring Nebula Morris & Podsiadlowski (2007)
Editor's Notes
- Ever wonder where come from?
- Ever wonder where come from?
- Personal connection remnants of a massive star billions yr ago
- Personal connection remnants of a massive star billions yr ago
- To understand why explode, energy source, stellar structureThis is our sun, giant ball of H gas hold by gravity, high Temp, what prevents it to collapse is the energy generation pressure
- To understand why explode, energy source, stellar structureThis is our sun, giant ball of H gas hold by gravity, high Temp, what prevents it to collapse is the energy generation pressure
- To understand why explode, energy source, stellar structureThis is our sun, giant ball of H gas hold by gravity, high Temp, what prevents it to collapse is the energy generation pressure
- Simplified pic, sun, < 8M_sun, stop at C
- Heavy, hot enough temperature, keep going on, until…
- At the end you’ll get a big onion
- Largest binding energy, can’t extract energy
- direct collapse into BH
- 1. Heavy elements produced in neutron rich high temp environment during bounce
- Iron core, very dense, turn into neutronsIn some cases, further collapse into BH
- White dwarf,Enough mass ~1.4M_sun, hot enough to ignite thermonuclear reaction suddenly
- 2 theories, accretion / merging of 2 WDignites thermonuclear reaction
- Always blow up at similar condition once critical mass achieved, so intrinsic brightness similar
- Always blow up at similar condition once critical mass achieved, so intrinsic brightness similar
- 950yr after explosion, faint, eventually disappear in ISM, 10kyr, 274 known remnants in milky way
- All visibe by naked eye
- Really takes off past decade, thx to the survey
- Too far to study the remnants, expansion, detailed morphology
- Too far to study the remnants, expansion, detailed morphology
- progenitor
- The most famous one is SN1987A, just outside our milky way, but just in our backyard 168k ly
- My work
- Hint of deceleration, not surprising, reverse shock takes time
- Nobody knows when’ll the next SN occur, but for sure, it’ll be a major event, holy grail