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D. Cutts
Barus-Holley 522
[email protected]
Physics
220
Astronomy
NGC 6369 “Little Ghost Nebula” in constellation Ophiucus
March 17, 2012
Physics 220 Lecture 13
original lecture slides were lost
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The slides for this lecture were lost. Some appear in Lecture 14, which
reviews the end stages of stars (covered first in this lecture) before discussing
neutron stars.
Topics:
pulsating stars: Cepheid variables: Period vs. luminosity relation
close binary star systems, Roche lobes and mass transfer
stellar evolution off the Main Sequence (after core H fusion ends)
M between 0.4 and 4 solar masses: shell H fusion > He flash > core He fusion
red giant > planetary nebula and white dwarfs; Chandrasekhar limit
M between 4 & 8 solar masses: core C fusion
M > 8 solar masses: becomes red supergiant, multiple layers of fusion in shells
until iron core >> core-collapse supernova [Types Ib, Ic or II] ( 99% of energy as neutrinos)
remnant core: neutron star or black hole (dep. on mass)
white dwarfs in close binary systems: can accrete matter > flash of C fusion in core (w. dwarf)
explodes in “thermonuclear” supernova (Type Ia) - no remnant core!
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Announcements:
today: Chapter 20 – the end stages after a star leaves the MS
Next week: Chapter 21 (Neutron Stars) and Chapter 22 (Black Holes)
Most of the 2011 lecture was given w/o powerpoint (some 2011 slides follow)
Showed the video Death of a Star, which describes the observation of
the supernova SN1987a
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