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Stars
Stars color determine its temperature.
Blue is hottest, red is coolest.
Sun is yellow, average temperature.
Stars made of mostly hydrogen and helium.
Can also contain carbon, nitrogen, and
oxygen.
Stars
 Continuous Spectrum
Full range of all colors (rainbow) of visible
light
 Emission Lines
Specific color emitted by elements in a
star
 Brightness
Absolute magnitude is how bright a star
would be if it was 32.6 light years from
Earth.
Apparent magnitude is how bright we see
it when we look outside.
Stars
Distance & motion of stars
Hard to measure as they are so far away-measured in light years.
Light-year = 9.46 trillion kilometers
Parallax is a shift in position throughout the
year that helps measure the distance.
Closer the star is the more parallax it will show.
Life cycle of Large Stars
Nebula—massive cloud of gas and dust
Protostar--gravity pulls it into a sphere
Main-sequence--Longest stage of life of
our stars
Supergiant--star expands outward and
cools, contracts, then…
Supernova—violent explosion expelling
outer layers of lighter elements. What
remains is…
Neutron Star, Black Hole, Pulsar
Life cycle of Medium Stars
Nebula—massive cloud of gas and dust
Protostar--gravity pulls it into a sphere
Main-sequence--Longest stage of life of
our stars
Redgiant--star expands outward and
cools, contracts, then…
White Dwarf—Small remnant of star with
the mass of 1.44 solar masses or less. No
more nuclear fusion.
Black Dwarf—Cold, dead star
Life cycle of Small Stars
Nebula—massive cloud of gas and dust
Protostar--gravity pulls it into a sphere
Main-sequence--Longest stage of life of
our stars. May last for trillions of years
White Dwarf—Exhausts al nuclear fusion,
then…
Black Dwarf--Cold, dead star
H-R Diagram
H-R diagram shows stars relationship between
their temperature and absolute magnitude.
Shows the stars’ life cycles.
Temperature on the bottom or x-axis.
Absolute magnitude is on the left or y-axis.
Massive stars
Massive stars are extremely hot so they have
short life spans as they burn fuel quickly.
Supernovas--Very large explosion that sends
layers of star into outer space.
Neutron stars--Small and extremely dense
star composed of neutrons.
Pulsars--A spinning neutron star that sends
out beams of radiation into space.
Black holes--Collapsed star that is very, very
dense that light cannot escape if it comes close
enough.
our Sun
H-R Diagram
Supernova
neutron star
black hole
pulsar