Astronomy Types of Stars Life Cycle of Stars Galaxies
Slide 2
Characteristics of Stars Color Color Gas Composition Gas
Composition Temperature Temperature Magnitude Magnitude
Slide 3
Color/ Temperature A stars surface temperature can be
determined by their color A stars surface temperature can be
determined by their color Blue stars have a temperature above
30,000 K Blue stars have a temperature above 30,000 K Red stars are
much cooler Red stars are much cooler Yellow stars have
temperatures between 5000 and 6000 K (such as our Sun) Yellow stars
have temperatures between 5000 and 6000 K (such as our Sun)
Slide 4
Binary Stars Binary Stars Binary Stars Pair of stars that orbit
around each other Pair of stars that orbit around each other Stars
are kept together by gravity Stars are kept together by gravity
More than half of all stars are binary or clusters More than half
of all stars are binary or clusters
Slide 5
Binary Stars: Sirius and its Tiny Companion
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Star Cluster Taken from Hubble Space Telescope
Slide 7
Star Distance Measurement A light-year is the best unit to
express stellar distance. A light-year is the best unit to express
stellar distance. It is the distance light travels in one year. It
is the distance light travels in one year. Example: A star that is
4.3 light-years away means that it takes 4.3 years for light from
that star to reach our Sun.
Slide 8
Magnitude This is how bright the star is (or appears to be)
This is how bright the star is (or appears to be) It can appear
brighter if It can appear brighter if The star is really close to
Earth The star is really close to Earth Actual brightness usually
depends on size Actual brightness usually depends on size
Slide 9
HertzsprungRussell Diagram
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Hertzsprung-Russell Diagram Shows relationship between a stars
magnitude and temperature Shows relationship between a stars
magnitude and temperature Main-Sequence line Main-Sequence line as
magnitude increases, so does temperature as magnitude increases, so
does temperature Notice how stars are colored blue, red, and
yellow!!!
Slide 11
HertzsprungRussell Diagram
Slide 12
H-R Diagram Almost 90% of all stars belong on the main-
sequence Almost 90% of all stars belong on the main- sequence The
brighter stars are the hottest (blue) The brighter stars are the
hottest (blue) 50 times more massive than Sun 50 times more massive
than Sun
Slide 13
H-R Diagram Continued In the upper right corner of diagram are
the red giants In the upper right corner of diagram are the red
giants Large red giants are called supergiants (Betelgeuse in
constellation Orion) Large red giants are called supergiants
(Betelgeuse in constellation Orion) In the lower-central part of
diagram are the white dwarfs In the lower-central part of diagram
are the white dwarfs
Slide 14
HertzsprungRussell Diagram
Slide 15
Where it all starts Cloud of Gas and Dust
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Birth of a Star Clouds of dust and gas in space 92% Hydrogen
and 7% Helium 92% Hydrogen and 7% Helium All stars must have
started with these gases. All stars must have started with these
gases. These clouds are also known as nebula These clouds are also
known as nebula
Slide 17
The Famous Eagle Nebula First taken by the Hubble Space
Telescope in 1995
Slide 18
Orion Nebula
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Gravity is important!! Gravity squeezes particles into the
center of the cloud of dust and gas Gravity squeezes particles into
the center of the cloud of dust and gas Without gravity, stars
would not develop!! Without gravity, stars would not develop!!
Slide 20
Balanced Forces
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Nuclear Fusion A star is born once nuclear fusion has begun A
star is born once nuclear fusion has begun Nuclear fusion is the
process of combining atoms to create tremendous amounts of energy.
Nuclear fusion is the process of combining atoms to create
tremendous amounts of energy. The first atoms to combine are
hydrogen. They combine to create helium. The first atoms to combine
are hydrogen. They combine to create helium.
Slide 22
Main-Sequence Stage Stars age at different rates while in the
main-sequence Stars age at different rates while in the
main-sequence Hot, massive blue stars burn their hydrogen really
fast Hot, massive blue stars burn their hydrogen really fast Yellow
stars (our sun) are in this stage for 10 billion years Yellow stars
(our sun) are in this stage for 10 billion years Remember: Our sun
is only 5 billion years old. So it still has 5 billion years left
just in this stage!! Remember: Our sun is only 5 billion years old.
So it still has 5 billion years left just in this stage!!
Slide 23
Yellow Star- Our Sun
Slide 24
Red-Giant Stage Star expands Star expands 100s to 1000s size of
main-sequence star 100s to 1000s size of main-sequence star Convert
helium to carbon to produce fuel and delay death Convert helium to
carbon to produce fuel and delay death Eventually all usable
elements will be burned Eventually all usable elements will be
burned Yellow stars (sun) usually spend less than a billion years
as a red giant Yellow stars (sun) usually spend less than a billion
years as a red giant
Slide 25
Burnout and Death A stars life cycle depends on the stars mass.
A stars life cycle depends on the stars mass. Medium Mass Stars and
Massive Stars will evolve and die differently Medium Mass Stars and
Massive Stars will evolve and die differently
Slide 26
Medium-Mass Stellar Death Medium-Mass Stars (our sun)
Medium-Mass Stars (our sun) Become red giants Become red giants
During collapse as red giant, create a round cloud of gas known as
a planetary nebula During collapse as red giant, create a round
cloud of gas known as a planetary nebula End as white dwarfs End as
white dwarfs The leftover centers of the star The leftover centers
of the star
Slide 27
Planetary Nebula Taken from Hubble Space Telescope
Slide 28
Planetary Nebula Taken from Hubble Space Telescope
Slide 29
High-Mass Stellar Death High-Mass Star High-Mass Star Red Giant
implodes and creates a supernova Red Giant implodes and creates a
supernova The gravity becomes too strong for the star to withstand
The gravity becomes too strong for the star to withstand Extremely
rare Extremely rare The last supernova to be seen with the naked
eye was in 1987. The last supernova to be seen with the naked eye
was in 1987. The explosion actually began before civilization began
here on Earth, but it took 169,000 years for the light from the
explosion to reach Earth. The explosion actually began before
civilization began here on Earth, but it took 169,000 years for the
light from the explosion to reach Earth.
Slide 30
Crab Nebula in the Constellation Taurus Taken from Hubble Space
Telescope
Slide 31
Supernova
Slide 32
Supernova Remnant Taken from Hubble Space Telescope
Slide 33
Star Remnants Black Holes Black Holes Remnants of supernova
event Remnants of supernova event These remnants are so massive
that they collapse These remnants are so massive that they collapse
Gravity is so strong that light can not escape Gravity is so strong
that light can not escape Black holes do not swallow up other stars
Black holes do not swallow up other stars However, some of the gas
and dust from the star may spiral into the black hole. However,
some of the gas and dust from the star may spiral into the black
hole. Black holes were first seen by x-ray waves. Black holes were
first seen by x-ray waves.
Slide 34
Black Hole Artists Drawing
Slide 35
Black Hole
Slide 36
Review Medium-Mass Stars Medium-Mass Stars Cloud of gas and
dust Cloud of gas and dust Main-Sequence Main-Sequence Red Giant
Red Giant Planetary Nebula Planetary Nebula White Dwarf White Dwarf
Massive Stars Massive Stars Cloud of gas and dust Main-Sequence
Supergiant Supernova Blackhole
Slide 37
Galaxies A galaxy is a group of stars, dust, and gases held
together by gravity A galaxy is a group of stars, dust, and gases
held together by gravity The smallest galaxies still contain a few
million stars. The smallest galaxies still contain a few million
stars. Galaxies were first classified by Edwin Hubble in the 1920s
Galaxies were first classified by Edwin Hubble in the 1920s Three
types of galaxies Three types of galaxies Spiral Spiral Elliptical
Elliptical Irregular Irregular
Slide 38
Types of Galaxies Spiral Spiral Disk-shaped with arms extending
from center Disk-shaped with arms extending from center 30% of
galaxies are spiral 30% of galaxies are spiral Our galaxy, the
Milky Way Galaxy Our galaxy, the Milky Way Galaxy The outer edges
of the spiral are blue because most of the blue stars in this
galaxy are located on the spirals arms The outer edges of the
spiral are blue because most of the blue stars in this galaxy are
located on the spirals arms The yellow and red stars are located in
the middle The yellow and red stars are located in the middle
Slide 39
Spiral Galaxy
Slide 40
www.hubblesite.org
Slide 41
Milky Way Galaxy Earths galaxy Earths galaxy Large spiral
galaxy Large spiral galaxy 100,000 light-years wide and 10,000
light-years thick 100,000 light-years wide and 10,000 light-years
thick
Slide 42
Structure of the Milky Way
Slide 43
Galaxies Continued Elliptical Elliptical Range in shape- round
to oval Range in shape- round to oval 60% of all galaxies are
elliptical 60% of all galaxies are elliptical These have very
bright centers These have very bright centers
Galaxies Continued Irregular Irregular No uniform shape No
uniform shape 10% of galaxies are irregular 10% of galaxies are
irregular Our nearest galaxy Our nearest galaxy
Slide 47
Irregular Galaxy
Slide 48
http://www.edmar-co.com/adriano/ccd/ccd3.htm
Slide 49
The Big Bang Theory Theory about the origin of the universe
Theory about the origin of the universe The Big Bang Theory: The
Big Bang Theory: At one time, the entire universe was confined to a
dense, hot, supermassive ball. (To the size of a tennis ball!) At
one time, the entire universe was confined to a dense, hot,
supermassive ball. (To the size of a tennis ball!) Then, about 13.7
billion years ago, a violent explosion occurred, hurling energy in
all directions Then, about 13.7 billion years ago, a violent
explosion occurred, hurling energy in all directions Some of the
expanding energy turned into matter Some of the expanding energy
turned into matter Matter made nebulas, which then made stars.
Stars eventually made galaxies. Matter made nebulas, which then
made stars. Stars eventually made galaxies.
Slide 50
The Big BangTheory
Slide 51
Supporting Evidence In 1964, Robert Wilson and Arno Penzias,
using a giant radio wave antenna, found radiation that was coming
to Earth from all directions in space In 1964, Robert Wilson and
Arno Penzias, using a giant radio wave antenna, found radiation
that was coming to Earth from all directions in space Called Cosmic
Background Radiation Called Cosmic Background Radiation This
radiation was actually created from the Big Bang. This radiation
was actually created from the Big Bang.
Slide 52
Future for the Universe? Two possible futures: Two possible
futures: The Universe will expand forever (most popular) The
Universe will expand forever (most popular) The outward expansion
will stop and inward contraction will begin The outward expansion
will stop and inward contraction will begin These are just
theories--- no one is certain how the Universe began and if it will
end. These are just theories--- no one is certain how the Universe
began and if it will end.
