1. Supernova and Neutron Stars
For heavy white dwarves with a companion star
acquire mass, if becomes > 1.4 M(Sun) SUPERNOVA (Ia). p + e  n + neutrino
Usually leaves neutron star
For high mass stars
fusion continues beyond C,O to Iron
if Mass(core) > 1.4 M(Sun) core collapses in SUPERNOVA (II)
leaves either Neutron Star or Black Hole
Most SN are this type
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2. White Dwarves Mass vs Radius
S. Chandrashekar worked out in 1930 on boat from India to England prior to grad school. Later became professor at Chicago. Nobel prize 1983
Earth radius
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3. Supernovas and Core Collapse
massive stars have fusion to heavier nuclei (Neon, Silicon, Sulpher, etc)
end up with core of Iron nuclei plus 26 unbound “free” electrons for every Fe
electrons are “degenerate” as so close together  provide most of the pressure resisting gravity
enormous stress. electrons “give way” leaves “hole” size of Earth in center of star
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4. Supergiant  Iron Core
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5. During Supernova breaks up many nuclei Fe  26p + 31n O  8p + 8n
core collapse gives 200 billion degrees  very high energy photons
breaks up many nuclei
Fe  26p + 31n O  8p + 8n
new nuclei form  photons, n, and p strike shell around core  see in SN debris
p + e  n + neutrino (and nuclei decaying)
1. Burst of neutrinos times more energy than from light (photons)
2. Leftover neutron star
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6. Core Collapse core collapses into mostly neutrons – very hot
outer layers rush into “hole” smashing into shock wave from core
Many nuclear reactions  form heavy elements
Core=30 km wide
Hole=13000 km wide
Type II expends energy increasing size
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7. Supernova Explosions
1 billion times brighter then the Sun for a few months
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8. Supernova 1987a (in movie)
Large Magellanic Cloud Type II 180,000 LY away
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9. Detection of neutrinos from SN1987A in Japan and Ohio
SN produced neutrinos
1015 n/cm2 at Earth
1018 neutrinos from SN passed through any person’s body
Traveled 175,000 light years to Earth
Passed through Earth
24 were detected in detectors made from 100 tons of water located in underground mines in Ohio, Russia and Japan
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10. Nuclear Synthesis up to Iron - fusion in Red Giants
All elements heavier than Helium are made inside stars
up to Iron - fusion in Red Giants
heavier than Iron (and some lighter) - Supernova explosions
Stars lose matter at end of life-cycle
becoming Red Giants (can detect)
Supernova debris (can detect)
and this matter forms new stars (and planets and us)
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11. Supernova Debris SN1987a
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12. Supernova Debris Crab Nebula M1
Supernova 1054 (observed by Chinese and Arabs). Has neutron star
Cassiopeia A maybe observed in 1680
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13. NEUTRON STARS In supernova explosion core collapses e- + p  n + n
neutrons remain giving neutron “star” about 1% protons/electrons
very hot (200 billion degrees) and very small (10-30 km - DeKalb County)
so very, very dense. 1 cm3  100 million tons
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14. Properties determined by “degenerate” electrons and neutrons.
White Dwarf
Neutron Star
Mass (relative to Sun)
1.0 (always < 1.4)
1.5 (always < 3)
Radius
5000 km
10 km
Density
106 g/cm3
1014 g/cm3
Properties determined by “degenerate” electrons and neutrons.
neutron/electron mass ratio = 2000, neutron star much smaller and denser
Senior level physics classes do the quantum mechanics which predict radius versus mass
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15. Angular Momentum + Neutron Stars
Angular momentum = MASS x VELOCITY x RADIUS decreasing RADIUS increases VELOCITY
Angular momentum is conserved: spinning chair ice skater formation of neutron star in collapse of larger spinning star

16. NEUTRON STARS II spin rapidly  from >100 Hz to less than 1 Hz
EM radiation from protons/electrons + spin  large magnetic fields
observe as repeating flashes of light PULSARS and seen in debris of known supernova explosions
discovered in 1967 by grad student Jocelyn Bell. Her advisor Anthony Hewitt won Nobel prize. Found in Crab Nebula where Chinese had recorded a supernova in First called LGM for “little green men”
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17. Crab Nebula
radio
infrared
period = 30 Hz or sec and can be “seen” in visible and X-ray
visible
X-ray
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18. Rotating Neutron Star
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