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!
Gold, Silver & More
Heavy Elements
Building Blocks of Life
Life from Exploding Stars! Without supernovae to disperse elements made in stars, no planets, no life!!
Why Study Supernova? They are cool most powerful explosions in the Universe J J 1,000,000,000,000,000,000,000,000,000 =
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
What is a Supernova? Nova= new star Naming: SN 2012A, …, SN2012Z, SN 2012aa,… SN 2012ab, …, SN 2012gh Death of a star, most powerful explosions: nuclear bombs brighter than a galaxy (~10 11 stars) more energy than the entire lifetime of a star SN 1994D
Historical Classification SN no H H Sino Si He no He Type IaType IbType IcType II
Physical Classification Thermonuclear Core Collapse SN no H H Sino Si He no He Type IaType IbType IcType II
Why do they explode? Stellar evolution Core collapse Thermonuclear
Life of a Sun-like Star Protostars White Dwarf Planetary Nebula Red Giant Sun-like Star Star-Forming Nebula
Life of a Massive Star Protostars Black Hole SUPERNOVA Red Supergiant Massive Star Star-Forming Nebula Neutron Star
self gravity gas pressure 2,000,000,000 x in 1 second! Pressure Balance
Stellar Alchemy
Life of a Sun-like Star Protostars White Dwarf Planetary Nebula Red Giant Sun-like Star Star-Forming Nebula
Massive Stars
Stellar Onion
Inert Iron Core
Stellar Onion not to scale
self gravity gas pressure Core Collapse
nuclear force Core Bounce
energy: J 99% neutrinos 1% kinetic energy 0.01% visible light produce heavy elements recycle light elements triggers new star formation
Compact Core
How about SN Type Ia?
White Dwarf Main Ingredient: White Dwarf
Mass Transfer
Accreting White Dwarf
Binary Merger
Standard Candles
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 G (~1868AD): not visible on Earth, too far and obscured
SN AD July 4 Crab Nebula (Messier 1)
Crab Nebula Remnant of SN1054 Harbors the Crab Pulsar --- most energetic neutron star found in the Milky Way
Historical Supernovae Tycho’s SN 1572AD November as bright as Venus visible until 1574 SN AD May 1 brightest SN observed visible for ~18months Kepler’s SN 1604AD October 9 visible in day time for 3 weeks
Can I See One Now? Catch one in the act? Go extragalactic! As of today, 6065 extragalactic SNe observed
Extragalactic SNe SN 2004et in NGC 6946SN 1994D in NGC 4526
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 168,000 light year
Observations Australia Telescope Compact Array Chandra X-ray Observatory OpticalX-rayRadio
Evolution
Expansion 35,000 km/s 4000 km/s
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
~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
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
SNR G
Triple-ring Structure
Triple Ring Nebula Morris & Podsiadlowski (2007)