Chapter 10 The Deaths of Stars Mass Transfer

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Chapter 10 The Deaths of Stars

Chapter 10 The Deaths of Stars

Mass Transfer in Binary Stars In a binary system, each star controls a finite

Mass Transfer in Binary Stars In a binary system, each star controls a finite region of space, bounded by the Roche Lobes (or Roche surfaces). Lagrange points = points of stability, where matter can remain without being pulled towards one of the stars. Matter can flow over from one star to another through the Inner Lagrange Point L 1.

Recycled Stellar Evolution Mass transfer in a binary system can significantly alter the stars’

Recycled Stellar Evolution Mass transfer in a binary system can significantly alter the stars’ masses and affect their stellar evolution.

White Dwarfs in Binary Systems Binary consisting of WD + MS or Red Giant

White Dwarfs in Binary Systems Binary consisting of WD + MS or Red Giant star => WD accretes matter from the companion Angular momentum conservation => accreted matter forms a disk, called accretion disk X-ray emission T ~ 106 K Matter in the accretion disk heats up to ~ 1 million K => X-ray emission => “X -ray binary”

Nova Explosions Hydrogen accreted through the accretion disk accumulates on the surface of the

Nova Explosions Hydrogen accreted through the accretion disk accumulates on the surface of the WD. Nova Cygni 1975 Þ Very hot, dense layer of non-fusing hydrogen on the WD surface Þ Explosive onset of H fusion Þ Nova explosion

Recurrent Novae In many cases, the mass transfer cycle resumes after a nova explosion.

Recurrent Novae In many cases, the mass transfer cycle resumes after a nova explosion. T Pyxidis → Cycle of repeating explosions every few years – decades

The Fate of our Sun and the End of Earth • The Sun will

The Fate of our Sun and the End of Earth • The Sun will expand to a Red giant in ~ 5 billion years. • Expands to ~ Earth’s radius • Earth will then be incinerated! • Sun may form a planetary nebula (but uncertain) • Sun’s C, O core will become a white dwarf

The Deaths of Massive Stars: Supernovae Final stages of fusion in high-mass stars (>

The Deaths of Massive Stars: Supernovae Final stages of fusion in high-mass stars (> 8 Msun), leading to the formation of an Iron core, happen extremely rapidly: Si burning lasts only for ~ 1 day Iron core ultimately collapses, triggering an explosion that destroys the star: A Supernova

Numerical Simulations of Supernova Explosions The details of supernova explosions are highly complex and

Numerical Simulations of Supernova Explosions The details of supernova explosions are highly complex and not quite understood yet.

Supernova Remnants X-rays The Crab Nebula: Remnant of a supernova observed in a. d.

Supernova Remnants X-rays The Crab Nebula: Remnant of a supernova observed in a. d. 1054 Optical The Cygnus Loop The Veil. ANebula Cassiopeia

Star Deaths Mass matters 1 Star Deaths StarsStar Deaths Mass matters 1 Star Deaths Stars
Chapter 11 Stars Properties of Stars Classifying StarsChapter 11 Stars Properties of Stars Classifying Stars
Atomic Mass and Formula Mass Atomic mass massAtomic Mass and Formula Mass Atomic mass mass
Mass transfer in binary systems Mass transfer occursMass transfer in binary systems Mass transfer occurs
Mass Transfer Coefficient Mass transfer coefficients simplified methodMass Transfer Coefficient Mass transfer coefficients simplified method
MHMT 14 Momentum Heat Mass Transfer Mass transferMHMT 14 Momentum Heat Mass Transfer Mass transfer
CHME 420 Mass Transfer 5 Mass Transfer EquipmentCHME 420 Mass Transfer 5 Mass Transfer Equipment
Mass Transfer by Diffusion General Considerations Mass transferMass Transfer by Diffusion General Considerations Mass transfer
CHME 420 Mass Transfer 5 Mass Transfer EquipmentCHME 420 Mass Transfer 5 Mass Transfer Equipment
Mass Transfer Mass Transfer Ficks First Law FluxMass Transfer Mass Transfer Ficks First Law Flux