PHY 111 Final Exam with answers |\ |\ |\ |\ |\
Until about 1920, it was believed that the Universe was
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
uniformly filled with stars. - CORRECT ANSWERS ✔✔The|\ |\ |\ |\ |\ |\ |\ |\
truth is that stars group into larger entities, the galaxies,
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
and our galaxy is called the Milky Way.
|\ |\ |\ |\ |\ |\ |\
The Appearance of the Milky Way (from the Earth) -
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
CORRECT ANSWERS ✔✔From the Earth, the Milky Way is a |\ |\ |\ |\ |\ |\ |\ |\ |\
hazy band running generally north to
|\ |\ |\ |\ |\ |\
south - looks similar to a cloud with the naked eye, but
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
you need a dark sky.
|\ |\ |\ |\
A small telescope, or even binoculars, reveals the cloud of
|\ |\ |\ |\ |\ |\ |\ |\ |\
the Milky Way is actually composed of: - CORRECT
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔thousands or millions of stars (~100 billion, |\ |\ |\ |\ |\ |\ |\ |\
if you could see all of them).
|\ |\ |\ |\ |\ |\
Why does the Milky Way appear like that to us? -
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
CORRECT ANSWERS ✔✔You always have to remember |\ |\ |\ |\ |\ |\ |\
that we're on the inside looking out; no one has ever seen
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
the Milky Way from the outside. The fact that we see it
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
|\ as a band of stars, tells us that it is generally disk shaped
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
,Based on observations and the appearance of other
|\ |\ |\ |\ |\ |\ |\ |\
galaxies, the MW likely has this basic structure and size - |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
CORRECT ANSWERS ✔✔bulge, disk, & halo |\ |\ |\ |\ |\
How did we determine the distance of the Milky Way? Two
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
Ways - CORRECT ANSWERS ✔✔1. Main Sequence Fitting
|\ |\ |\ |\ |\ |\ |\ |\
2. Cepheid Variables
|\ |\
Main Sequence Fitting (also called Spectoscopic Parallax):
|\ |\ |\ |\ |\ |\
- CORRECT ANSWERS ✔✔For Main Sequence stars, we
|\ |\ |\ |\ |\ |\ |\ |\ |\
can always determine the Spectral Type and the Apparent
|\ |\ |\ |\ |\ |\ |\ |\
Magnitude or Brightness. Then, the HR diagram gives the
|\ |\ |\ |\ |\ |\ |\ |\ |\
Absolute Magnitude or Luminosity.
|\ |\ |\ |\
• If we know the Luminosity and Apparent Brightness, the
|\ |\ |\ |\ |\ |\ |\ |\ |\
inverse square
|\ |\
|\ law gives the distance.
|\ |\ |\
• Since the main sequence is a band, there is
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
considerable uncertainty |\
Cepheid Variables - CORRECT ANSWERS ✔✔In 1916, |\ |\ |\ |\ |\ |\ |\
Henrietta Leavitt was studying stars call Cepheid |\ |\ |\ |\ |\ |\ |\
Variables
• Cepheids are extremely luminous giant stars that
|\ |\ |\ |\ |\ |\ |\ |\
pulsate
, • Leavitt discovered the "Period - Luminosity" for
|\ |\ |\ |\ |\ |\ |\ |\
Cepheids
• Using Cepheids, Harlow Shapley could measure the
|\ |\ |\ |\ |\ |\ |\ |\
distance
|\ to globular clusters and determine the size of the MW.
|\ |\ |\ |\ |\ |\ |\ |\ |\
• Since Cepheids are so bright, they've been used to
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
determine
|\ distances both inside and outside the MW |\ |\ |\ |\ |\ |\
Just like the planets in our solar system: - CORRECT
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔the stars in the MW are in constant |\ |\ |\ |\ |\ |\ |\ |\
motion about the galactic center |\ |\ |\ |\
How stars in the MW move: - CORRECT ANSWERS
|\ |\ |\ |\ |\ |\ |\ |\ |\
✔✔Stars in the Bulge and the Halo follow randomly |\ |\ |\ |\ |\ |\ |\ |\ |\
oriented orbits |\
• Stars and gas in the disk follow roughly circular orbits
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
around the galactic center (the Sun completes one orbit
|\ |\ |\ |\ |\ |\ |\ |\ |\
in about 220
|\ |\
|\ million years) |\
What causes this flat rotation curve? - CORRECT
|\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔Dark Matter is nonluminous matter that is |\ |\ |\ |\ |\ |\ |\ |\
believed to exist |\ |\
|\ in the halos of spiral galaxies
|\ |\ |\ |\ |\
Until about 1920, it was believed that the Universe was
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
uniformly filled with stars. - CORRECT ANSWERS ✔✔The|\ |\ |\ |\ |\ |\ |\ |\
truth is that stars group into larger entities, the galaxies,
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
and our galaxy is called the Milky Way.
|\ |\ |\ |\ |\ |\ |\
The Appearance of the Milky Way (from the Earth) -
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
CORRECT ANSWERS ✔✔From the Earth, the Milky Way is a |\ |\ |\ |\ |\ |\ |\ |\ |\
hazy band running generally north to
|\ |\ |\ |\ |\ |\
south - looks similar to a cloud with the naked eye, but
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
you need a dark sky.
|\ |\ |\ |\
A small telescope, or even binoculars, reveals the cloud of
|\ |\ |\ |\ |\ |\ |\ |\ |\
the Milky Way is actually composed of: - CORRECT
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔thousands or millions of stars (~100 billion, |\ |\ |\ |\ |\ |\ |\ |\
if you could see all of them).
|\ |\ |\ |\ |\ |\
Why does the Milky Way appear like that to us? -
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
CORRECT ANSWERS ✔✔You always have to remember |\ |\ |\ |\ |\ |\ |\
that we're on the inside looking out; no one has ever seen
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
the Milky Way from the outside. The fact that we see it
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
|\ as a band of stars, tells us that it is generally disk shaped
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
,Based on observations and the appearance of other
|\ |\ |\ |\ |\ |\ |\ |\
galaxies, the MW likely has this basic structure and size - |\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
CORRECT ANSWERS ✔✔bulge, disk, & halo |\ |\ |\ |\ |\
How did we determine the distance of the Milky Way? Two
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
Ways - CORRECT ANSWERS ✔✔1. Main Sequence Fitting
|\ |\ |\ |\ |\ |\ |\ |\
2. Cepheid Variables
|\ |\
Main Sequence Fitting (also called Spectoscopic Parallax):
|\ |\ |\ |\ |\ |\
- CORRECT ANSWERS ✔✔For Main Sequence stars, we
|\ |\ |\ |\ |\ |\ |\ |\ |\
can always determine the Spectral Type and the Apparent
|\ |\ |\ |\ |\ |\ |\ |\
Magnitude or Brightness. Then, the HR diagram gives the
|\ |\ |\ |\ |\ |\ |\ |\ |\
Absolute Magnitude or Luminosity.
|\ |\ |\ |\
• If we know the Luminosity and Apparent Brightness, the
|\ |\ |\ |\ |\ |\ |\ |\ |\
inverse square
|\ |\
|\ law gives the distance.
|\ |\ |\
• Since the main sequence is a band, there is
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
considerable uncertainty |\
Cepheid Variables - CORRECT ANSWERS ✔✔In 1916, |\ |\ |\ |\ |\ |\ |\
Henrietta Leavitt was studying stars call Cepheid |\ |\ |\ |\ |\ |\ |\
Variables
• Cepheids are extremely luminous giant stars that
|\ |\ |\ |\ |\ |\ |\ |\
pulsate
, • Leavitt discovered the "Period - Luminosity" for
|\ |\ |\ |\ |\ |\ |\ |\
Cepheids
• Using Cepheids, Harlow Shapley could measure the
|\ |\ |\ |\ |\ |\ |\ |\
distance
|\ to globular clusters and determine the size of the MW.
|\ |\ |\ |\ |\ |\ |\ |\ |\
• Since Cepheids are so bright, they've been used to
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
determine
|\ distances both inside and outside the MW |\ |\ |\ |\ |\ |\
Just like the planets in our solar system: - CORRECT
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔the stars in the MW are in constant |\ |\ |\ |\ |\ |\ |\ |\
motion about the galactic center |\ |\ |\ |\
How stars in the MW move: - CORRECT ANSWERS
|\ |\ |\ |\ |\ |\ |\ |\ |\
✔✔Stars in the Bulge and the Halo follow randomly |\ |\ |\ |\ |\ |\ |\ |\ |\
oriented orbits |\
• Stars and gas in the disk follow roughly circular orbits
|\ |\ |\ |\ |\ |\ |\ |\ |\ |\ |\
around the galactic center (the Sun completes one orbit
|\ |\ |\ |\ |\ |\ |\ |\ |\
in about 220
|\ |\
|\ million years) |\
What causes this flat rotation curve? - CORRECT
|\ |\ |\ |\ |\ |\ |\ |\
ANSWERS ✔✔Dark Matter is nonluminous matter that is |\ |\ |\ |\ |\ |\ |\ |\
believed to exist |\ |\
|\ in the halos of spiral galaxies
|\ |\ |\ |\ |\
