Astro 10

Front 1

Giant star

Back 1

1.core uses up all hydrogen
2.helium accumulates in core, nuclear reactions cease
3.core contracts b/c of gravity and grows hotter..core heats hydrogen shell
4.hydrogen fusion begins in shell around core
5.radiation energy from shell pushes outward, outer layers swell
6.as gas expands, it cools

Front 2

giant star evolution

Back 2

red giant= large radius, cool (red) temp
as star expands, temp decreases and luminosity increases

Front 3

helium fusion

Back 3

as core shrinks, temp increases until hot enough for Helium to fuse.

Tri-Alpha process: 3 Helium nuclei fuse into 1 carbon nucleus

Front 4

Helium flash

Back 4

explosive ignition of Helium fusion in core of giant star

core temp expands and increases until fusion becomes stable

Front 5

degenerate matter

Back 5

gas so dense that electrons cannot change their energy.
gas resists compression

Front 6

in stars like sun..

Back 6

0.4-4 solar mass
temp and pressure in core never high enough for carbon fusion
outer layers are loose/blow away
hot interior releases high speed wind

Front 7

planetary nebulae

Back 7

an expanding shell of gas ejected from star during the latter stages of its evolution

Front 8

white dwarf

Back 8

after outer layers blown away, if solar mass less than 1.4, no more fusion.

=hot small objects with low luminosity

eventually will radiate away its heat and become black dwarf

Front 9

novae

Back 9

sudden brightening of star due to eruptions on white dwarf in a binary system

material from nearby companion star fall toward white dwarf, creating accretion disk.
density and temp increase and violent hydrogen fusion

Front 10

red dwarfs

Back 10

less than 0.4 solar mass

hydrogen fusion lasts for long time, never accumulates helium in core

never evolve into giant stars or beyond

Front 11

massive stars

Back 11

evolve off main sequence to become giant or supergiant

core hot enough for carbon fusion, higher elements fuse away in onion layer, at core. fusion stops at iron

Front 12

Type II Supernovae

Back 12

explosive death of high mass star. spectra rich in hydrogen gases

core/outer layers collapse inward, shock wave of energy moves outward

Front 13

Type I supernovae

Back 13

explosive death of white dwarf, which accreated material from a companion star

extra material pushes mass over 1.4, carbon fusion occurs

Front 14

supernovae remenants

Back 14

remain for tens of thousands of years. add metals to interstellar medium...later generations of stars have higher metal content

Front 15

Neutron stars

Back 15

when massive star goes supernovae, mass is more than 1.4

protons forced to combine w/ electrons to create neutrons. gravity halted

Front 16

pulsars

Back 16

magnetic axis of neutron star inclined to rotational axis. rotation sweeps beam like lighthouse
Earth- detect a pulse but not energy

Front 17

X ray bursters

Back 17

sudden brightening star associated with eruptions on neutron star in binary system

higher energy than novae

Front 18

black hole

Back 18

if mass more than 2-3, gravity stronger than neutron pressure. star collapses to point singularity

not even light can escape

event horizon= boundary where no radiation can escape

Front 19

curved space

Back 19

massive objects curve space around them

more massive=more curvature

Front 20

falling into black hole

Back 20

as object nears event horizon, tidal forces rip object apart.
object heats as it falls, radiates x-ray

Front 21

detection of black holes

Back 21

matter flows from star into accretion disk around an unseen companion (whos mass is at least 3=black hole)

Front 22

star cluster

Back 22

open cluster: 10-1000 stars in region 25 pc in diameter
globular cluster: 10^5-10^6 stars in 10-30 pc region