Download Stars - Moodle

Name
Block
Stars
Chapter 30
Pages 775-
Star
• A ball of gases that gives off a
tremendous amount of
___________________________
___________________________
• Notice that I did not say __________
• Stars emit all
______________________ of the
EM spectrum
Analyzing Starlight
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Astronomers analyze stars by looking at the light they emit
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Stars produce a display of colors and lines called a _________________
They use a ____________________________________
A spectrograph _______________ light into different colors or
wavelengths
Three types of spectra
• ____________________________ or bright line
• _____________________________or dark line—dark line shows
composition and temperature
• _____________________________
Star classification
• If we look at a star with a spectroscope we
see ______________lines called absorption
spectra
• These lines indicate the stars
______________________
_____________________________
The most common element in stars is
__________________________________
Each chemical element has a characteristic
spectra in a given range of temperatures
The colors and lines indicate the
___________________that make up a star
Name
Block
Color and Stars
Think of a candle
• Hottest part is ________________
• Red is the cool part at the top
Apparent Motion of Stars
• Time lapse photography show a circular pattern revolving around the star
______________________________
• We know Polaris as the North Star
• It is located directly above the North Pole so as the Earth spins the stars
appear to move
Doppler Effect
The apparent shift in the wavelength of light emitted by a light source moving
____________ or ________________ from a viewer
Which way is the color shifted if the object is moving toward the viewer?
Which way is the color shifted if the object is moving away from the viewer?
Which color shift do we observe?
Parallax
The apparent shift in a stars location when viewed from different locations in
orbit
The _________________ the star is, the __________________ it appears to
move
Absolute vs. Apparent Magnitude
• Absolute—how bright a star _______________________is
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Apparent—how bright it __________________________from Earth
Name
Block
Stellar Evolution
Section 2
Page 781
The Hertzsprung Russell diagram –HR Diagram
– 90% of stars are found on a diagonal
line called the __________
_____________
– Hotter on the left cooler on the right
– Brighter at top dimmer at bottom
Groups of Stars
• ________ ____________—diagonal line
• Red Giants– _________ and __________
• Supergiants—brighter and cooler
• White Dwarfs—___________ and hot
Spectral Class
• OBAFGKM
• Oh Be A Fine Girl Kiss Me
Birth of Stars
• Nebula—interstellar clouds of _____________and ___________________
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Drawn together by gravitational attraction called accretion
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This huge ball of gas is called a ___________________________
Begins to ________________ as it condenses
Birth of a star
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This ball continues to be drawn together by gravitational attraction
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This produces a huge amount of radiant and thermal energy
When temperatures inside reach about _________________ Kelvins nuclear
________________________begins
___________________ of nuclear fuel marks the change from protostar to
star
Main sequence star
• Most of a star’s life is spent as a _____________ ___________________ star
• Its size, temperature, and color are relatively ________________________
• During this time it burns up its supply of _____________________
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Block
• What happens next depends on the star’s __________________
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When the sun has burned all its _______________, the helium core will
____________________ because of gravity
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The rise in temperature will ignite the _____________ in the core and
the core expands to become a _________ ____________________
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Our sun will reach this stage in about ____ ________________ years
A Red Giant you know—_____________________________
The Fate of Stars differs according to their ____________________
(Low mass stars)
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Small stars will shrink and throw off the outer layers in rings becoming a
__________________________ _________________________
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The shrunken core that remains is a ___________________
_________________
– There is no nuclear fusion, it is only _______________________ hot
– If it is a binary star it may form a nova,
or,
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When the core cools it becomes a ___________________ dwarf
Medium Mass stars—like the sun
? Become RED GIANTS
• Starts to burn helium-contracts because of gravity
• This raises the temperature and the star expands
• Our sun will reach this stage about ____________________ years from now
White Dwarf
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What remains after the star swells and ejects the outer layers
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A cold, dark lump of matter that remains when a star has burned out and
cooled off
What remains no longer burns _________________
It slowly cools
It is now a stellar remnant
It can change color as it cools
Black Dwarf
Life cycle of a low mass star
1. Protostar-formed from nebula
2. Main sequence
3. Red Giant
4. Planetary nebula
5. White dwarf
6. Black Dwarf
Name
Block
High mass stars have a different fate—they burn faster and
• After the main sequence, stars with a mass much greater than the sun can
burn and create larger and larger elements
• When it gets to iron, it takes too much energy to create other elements so it
collapses
• This causes a ___________________, this is when heavier elements are made
• Generate the elements of life
• After a supernova a high mass star may become a
• _______________________ star
• The inner part implodes to form a super dense neutron star-- protons
and electrons have fused to form neutrons
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Or, if it is VERY massive it may form a ______________ ______________
Life Cycle of a High Mass Star
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Protostar
Main sequence
Red giant or red supergiant
Supernova
Neutron star or black hole
Black Holes
Singularity—density is infinite
Event horizon—_______________ ______ _______ _____________________
Answer these questions
Revisit the HR diagram
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Where are stars most of their lives?
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Where are they when they begin to die?
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What are they after they use up their fuel?
How is the Life cycle of a high mass different????