Download Chapter 29 Notes

Chapter 29 Notes
Stars
The Sun: Solar Atmosphere
• Photoshere:
visible surface,
5800 K
• Chromosphere:
30,000 K
• Corona: 1 to 2
million K, solar
wind extends
from the corona
Solar Interior
• Core: nuclear fusion
• Radiative zone:
energy moves
outward from the
core
• Convective zone:
currents carry
energy to the surface
Solar Activity
• Sunspots—11 year cycle
• Solar wind
• Prominences
Solar Energy
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Nuclear fusion takes place in the core of the sun
Hydrogen nuclei fuse together to form helium
Energy is released
E=mc2 (E = Energy, m = mass, c = speed of light)
• When hydrogen is gone, stars will form carbon,
oxygen, neon, silicon, and iron—in that order
Electromagnetic Spectrum
• Dark bands in the
visible spectrum
are caused by
different chemical
elements
• 70% hydrogen
28% helium
Measuring Stars
• Parallax is used to find the
distance to stars
• Constellations: Groups of stars
in the same part of the sky
• Clusters: groups of stars bound
together by gravity
• Binaries: two stars that orbit a
common center of mass
Doppler Shift
• Movement of a
star affects the
frequency of the
light waves
• Stars moving
toward us are
blueshifted, stars
moving away are
redshifted
Star Properties
• Magnitude
– Apparent magnitude: how bright the star appears
from Earth
– Absolute magnitude: how bright a star would look
if it were 10 parsecs away
• Luminosity: energy output per second
• Composition of stars: ~73% hydrogen, ~25%
helium, ~2% all other elements
Temperature
• Temperature
determines
spectral class
and color
• Blue stars are
hotter, red
stars are cooler
• Oh, be a fine
girl, kiss me.
Spectral Types of Stars
Star Life Cycle
• Stars spend most of their “life” in the Main
Sequence and so most stars are located in the
Main Sequence section of the H-R diagram
• Small mass stars burn fuel slowly and have a
long life span
• Large mass stars burn their fuel very quickly
and are much brighter than small mass stars
Star “Life-Cycle”
• Mass determines the future of a star