Stars, Galaxies

1
Stars, Galaxies Universe

• Chapter 3

2
Tools of Astronomy

• Constellations are groups of stars that form a
  pattern.
• The electromagnetic spectrum is made of radio
  waves, infrared radiation, visible light,
  ultraviolet radiation, x-rays, and gamma rays.

3
Refracting Telescope

• Refracting telescope collects light using lenses.
  
• The lenses bend the light to the focal point.

4
Reflecting Telescope

• Reflecting telescope uses a mirror to collect the
  light.
• A concave mirror bends the light inward to a
  focal point.

5
Radio Telescope

• Radio telescopes collects radio waves.
• The collector is a concave dish.

6
Observatory

• The building that houses a telescope is called an
  observatory.

7
Other Tools of Astronomy

• Telescopes have been put into space on satellites
  space stations.
• Spectrographs gather information about stars such
  as a stars composition temperature.

8
Characteristics of Stars

• A galaxy contains hundreds of billions of stars.
• The universe contains billions of galaxies.

9
Distances to Stars

• A light year is the distance light travels in
  year.
• Astronomers often use parallax to measure
  distances to nearby stars.
• Parallax is the apparent change in position of an
  object when you look at it from different places.

10
Classifying Stars

• Stars are classified by size, temperature, and
  brightness.
• Temperature of a star is indicated by color, hot
  stars are blue cooler stars are red.
• Apparent brightness is the brightness of a star
  as observed from earth.
• Absolute magnitude is the brightness of a star
  observed at the distance of 10 parsecs.

11
Hertzsprung-Russell Diagram

• H-R diagram is a graph of the Milky Way galaxy.
• Surface temperature is graphed on the x-axis.
• Absolute magnitude is graphed on the y-axis.

12
Types of Stars

• Blue super giants have a high brightness and high
  temperature.
• Red giants super giants have a high brightness
  and low temperature.
• White dwarfs have a low brightness and high
  temperature.
• 90 of all stars appear on the Main Sequence
  going from the upper right to the lower left
  corner.

13
Birth of a Star

• A star begins as a cloud of gas and dust called a
  nebula.
• Gravity pulls the gas and dust together into a
  protostar.
• A star is born when the contracting gas and dust
  becomes so hot that nuclear fusion begins.

14
Length of Life of a Star

• More massive stars live short lives of millions
  of years.
• Less massive stars live long lives of billions of
  years.
• The sun will live for 9-10 billion years.

15
During the Life Cycle of a Star

• Stars fuse hydrogen into helium during most of
  their lives.
• After all the hydrogen has been fused into
  helium, the star fuses helium into carbon, carbon
  into oxygen and then oxygen into iron.

16
Death of a Star

• Stars use up their hydrogen and expand their
  atmosphere.
• Stars that are less than 1.4 solar masses will
  shrink to a white dwarf.
• Stars between 1.4 -3.0 solar masses will produce
  a supernova and leave a neutron star.
• Stars more than 3.0 solar masses will produce a
  supernova and collapse into a black hole.

17
Star Systems

• Most stars are members of groups of two or more
  stars called star systems.
• Star systems with two stars are called double
  stars or binary stars.
• Binary eclipsing stars are stars where one star
  blocks the light from another.

18
One of the greatest advancements in astronomy was
the telescope. Which is the correct order of
advancements?

• Radio- refracting-reflecting
• Reflecting refracting radio
• Refracting-reflecting-radio
• Radio- reflecting-refracting

19
Why do astronomers measure interstellar distances
in light years instead of kilometers or miles?

• Light years are a measure of time.
• Miles and kilometers are too small of a unit.
• Miles and kilometers are too large of a unit.
• I dont have a clue . . . help me!

20
Which of the following correctly shows the age
progression of an average star?

• Main sequence?White Dwarf?Red Giant ?Nebula
• Red Giant ?White Dwarf ?Main Sequence ?Nebula
• Nebula ?Main Sequence ?Red Giant ?White Dwarf
• White Dwarf ?Red Giant ?Main Sequence ?Nebula

21
What is the next likely stage of a protostar?

• Super Giants
• Nova
• Main Sequence
• Neutron Star

22
Galaxies

• Galaxies are a group of billions of stars.
• Type of galaxies are
• Elliptical
• Spiral
• Irregular

23
Elliptical Galaxy

• Old galaxy.
• Contains red star that are old.
• No gas or dust.

24
Spiral Galaxy

• Middle aged galaxy.
• Contains blue stars.
• Has some dust and gas.
• Our Milky Way is a spiral galaxy.

25
Irregular Galaxy

• Unorganized collection of stars.
• Made of very young stars.
• Has a great deal of gas and dust.

26
History of the Universe

• Edwin Hubble discovered that the farther away a
  galaxy is from us, the faster it is moving away
  from us.
• Stars moving away from us shows a red shift.

27
Big Bang Theory

• Big Bang Theory suggest that billions of years
  ago, the universe was small, hot and dense and
  then the universe exploded.
• The universe formed in this enormous explosion
  about 10 to 15 billion years ago.

28
Formation of the Solar System

• The solar system formed 5 billion years ago.
• The solar system formed from a giant cloud of gas
  and dust, or nebula.

29
Future of the Universe

• The universe may continue to expand.
• Gravity may pull the universe back together.

30
What type of galaxy is shown in the picture?

• Irregular
• Spiral
• Elliptical
• D. I have no idea I need help!!!

31
Review Questions

• What are the three types of galaxies?
• elliptical, spiral irregular
• Distances between stars are measured in units
  called _______.
• light years
• Stars begin as a cloud of gas dust known as a
  __________.
• nebula

32
Review Questions

• What does the length of life of a star depends
  on?
• mass of the star
• What is the name of our galaxy?
• Milky Way
• What type of galaxy is the Milky Way?
• spiral
• What is the name of the theory of the creation of
  the universe?
• Big Bang

33
Review Questions

• What type of tools are used to study the
  universe?
• telescope
• Which type of telescope uses mirrors?
• reflecting
• Which type of telescope uses lenses?
• refracting

34
Review Questions

• What indicates how hot a star is?
• color of the star
• During nuclear fusion, what does hydrogen fuse
  into?
• helium
• What is graphed on the H-R diagram?
• brightness temperature

35
Review Questions

• What is the brightness of a star as seen from
  earth?
• apparent brightness
• What is the brightness of a star that is seen at
  a standard distance of ten parsecs?
• absolute magnitude

36
Review Questions

• What process is used to measure the distance of
  nearby stars?
• parallax
• What type of telescope collect electromagnetic
  waves other than light?
• radio telescope
• How long ago did the Big Bang occur?
• 10-15 billion years ago

37
Review Questions

• What are patterns of stars in the sky called?
• Constellations
• What is the building called that has a telescope?
• Observatory
• Which type of galaxy has red stars and no gas or
  dust?
• elliptical

38
Review Questions

• Which type of galaxy has blue stars and some gas
  dust?
• spiral galaxy
• Galaxies are classified by their _______.
• shape
• Who proposed that the universe is expanding?
• Hubble

39
Review Questions

• What evidence do we have that the universe is
  expanding?
• red shift
• What happens to a small star at its death?
• white dwarf
• What happens to a very large star at its death?
• Supernova to a black hole

40
Practice Extended Answer Questions

• Describe the life cycle of a star.
• What are the three types of telescopes and how
  are they different?
• Explain the H-R diagram.
• How does the mass of a star affect the length of
  life of a star?
• How do the different types of galaxies compare?
• Explain the Big Bang Theory.