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.
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
30. Core Bounce
energy: 1046J
99% neutrinos
1% kinetic energy
0.01% visible light
produce heavy
elements
recycle light
elements
triggers new
star formation
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
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
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
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
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