9 - Cosmic Explosions and Black Hole

9 - Cosmic Explosions and Black Hole - High Mass Star death...

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Supernovae ==> neutron stars ==> pulsars stellar mass black holes High Mass Star death : Crab Nebula -- SN 1054AD, 30 ms pulsar and pulsar wind X-ray Visible light pulsar visible light 30ms framing
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the expanding SN shell is an important source of KE to interstellar gases initally moving outwards at 10 4 km/s slows down as it encounters interstellar gas eventually ring breaks up Cas A SN Veil Nebula Cygnus SN Vela SN
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Binary pulsar 1974-- Russell Hulse and Joe Taylor discovered a pulsar w/ period 59 ms in a close binary system. Pulse arrival times ==> eccentric orbit (e = 0.62) period of 7.8 hours orbit sep. ~ R (0.7 – 3.1 million km) change in orbit consistent w/ GR prediction of gravity waves ==> Nobel prize
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change in time of periastron (closest approach) matches the GR prediction Orbit shrinks by ~3 mm !! per orbit of binary * ʼ s Binary pulsar orbit rotation
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Neutron star structure Solid crust -- extremely smooth w/ mountains few mm Liquid interior -- mostly neutrons (few e - + ) ==> neutron superconductor & superFuid ~10 km
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vela pulsar neutron star quakes ?? discontinuous pulsar period changes suggest moment of inertia changed ==> n-star quakes (or vortices)
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can also spin up n* or pulsar with accretion in binary system accounts for the very short millisec pulsars
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Stars above 3 M sun ==> black hole
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for n-star, escape velocity : V esc = (2 G M / R ) 1/2 ~ 0.2 c popular way of conceptualizing BH : larger M or smaller R V esc c M = 1 M , R = 3 km => V esc = c
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This document was uploaded on 01/12/2012.

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9 - Cosmic Explosions and Black Hole - High Mass Star death...

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