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How fast would a galaxy 2,000
megaparsecs away be moving with respect
to us, according to Hubble’s Law? Hint: H0 =
70 km/s/Mpc
a) 1,400 km/s
b) 14,000 km/s
c) 140,000 km/s
d) 140 km/s
How fast would a galaxy 2,000
megaparsecs away be moving with respect
to us, according to Hubble’s Law? Hint: H0 =
70 km/s/Mpc
a) 1,400 km/s
b) 14,000 km/s
c) 140,000 km/s
d) 140 km/s
The number of stars in the galaxy is
approximately ____________.
a) 2-5 billions
b) 50-100 millions
c) 100-400 billions
d) 50-80 billion
The number of stars in the galaxy is
approximately ____________.
a) 2-5 billions
b) 50-100 millions
c) 100-400 billions
d) 50-80 billion
The number of stars in the galaxy is
approximately ____________.
a) 2-5 billions
b) 50-100 millions
c) 100-400 billions
d) 50-80 billion
If a galaxy is at a distance of one billion light
years, then which is true?
a)
We see the galaxy the way it was one billion years
ago
b) We see the galaxy the way it was when the Universe
was one billion years old
c) We have no knowledge of anything at that distance
d) We see the galaxy the way it will be in one billion
years
If a galaxy is at a distance of one billion light
years, then which is true?
a)
We see the galaxy the way it was one billion
years ago
b) We see the galaxy the way it was when the Universe
was one billion years old
c) We have no knowledge of anything at that distance
d) We see the galaxy the way it will be in one billion
years
Which of the following galaxy types contains
stars but almost no gas?
a) Barred spiral
b) Spiral
c) Elliptical
d) Irregular
Which of the following galaxy types contains
stars but almost no gas?
a) Barred spiral
b) Spiral
c) Elliptical
d) Irregular
All known galaxies are moving away from us
and thus are redshifted
a) TRUE
b) FALSE
All known galaxies are moving away from us
and thus are redshifted
a) TRUE
b) FALSE
What distance measurement technique
works best for the closest galaxies that we
can observe?
a) Radar
b) Cepheid
c) Parallax
d) White dwarf supernovae
What distance measurement technique
works best for the closest galaxies that we
can observe?
a) Radar
b) Cepheid
c) Parallax
d) White dwarf supernovae
The mass of the galaxy is approximately
______ solar masses.
a) 100
b) 15,000,000
c) 600,000
d) 850,000,000,000
The mass of the galaxy is approximately
______ solar masses.
a) 100
b) 15,000,000
c) 600,000
d) 850,000,000,000
Gas, dust, and spiral arms are found in the
galactic ______.
a) Bulge
b) Disk
c) Halo
Gas, dust, and spiral arms are found in the
galactic ______.
a) Bulge
b) Disk
c) Halo
Spiral arms do not contain
a) Open clusters
b) Supermassive black holes
c) High stellar densities
d) Star forming regions
Spiral arms do not contain
a) Open clusters
b) Supermassive black holes
c) High stellar densities
d) Star forming regions
Which of the following is the Milky Way
Galaxy
a) Barred spiral
b) Spiral
c) Irregular
d) Elliptical
Which of the following is the Milky Way
Galaxy
a) Barred spiral
b) Spiral
c) Irregular
d) Elliptical
Which of the following is a standard candle
used to measure the distance to distant
galaxies?
a) Doppler effect
b) Parallax
c) Radar
d) Tully-Fisher relation
Which of the following is a standard candle
used to measure the distance to distant
galaxies?
a) Doppler effect
b) Parallax
c) Radar
d) Tully-Fisher relation
The oldest stars are likely to be found in the:
a) Halo
b) Bulge
c) Disk
The oldest stars are likely to be found in the:
a) Halo
b) Bulge
c) Disk
What is the cosmological principal?
a) The Universe looks about the same
everywhere
b) Dark matter fights dark energy
c) The Universe was created during the Big
Bang event
d) The Universe is expanding
What is the cosmological principal?
a) The Universe looks about the same
everywhere
b) Dark matter fights dark energy
c) The Universe was created during the Big
Bang event
d) The Universe is expanding
Edwin Hubble used observations of
_______ to determine the distance to the
Andromeda Galaxy
a) Cepheids
b) Comets
c) Neutron stars
d) White dwarfs
Edwin Hubble used observations of
_______ to determine the distance to the
Andromeda Galaxy
a) Cepheids
b) Comets
c) Neutron stars
d) White dwarfs
Which galaxy is closest to us?
a) The Small Magellanic Cloud
b) The Large Magellanic Cloud
c) The Andromeda Galaxy
d) The Sagittarius Dwarf Spheroidal Galaxy
Which galaxy is closest to us?
a) The Small Magellanic Cloud
b) The Large Magellanic Cloud
c) The Andromeda Galaxy
d) The Sagittarius Dwarf Spheroidal
Galaxy
The Milky
Way
Active
Galactic
Nuclei
Galaxy
Evolution
The Cosmic
Distance
Ladder
Types of
Galaxies
Supermassive
Black Holes
$100
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What type of galaxy is the Milky Way?
A barred spiral
type
What is the closest galaxy to the Milky Way?
Sagittarius
Dwarf
Spheroidal
Galaxy
Roughly how many stars are located in the
Milky Way?
100-400 billion
In 1 trillion years, the Milky Way will have
little gas, if any. Where will the matter that
comprised the current gas be located?
Mostly locked into white dwarfs and low-mass
stars
Roughly how long does it take for the Sun to
complete one orbit around the Milky Way
230 million years
What types of stars are found in each of the
three major components of a galaxy like the
Milky Way?
Disk: Mostly young stars
Central Bulge: Mix of old and young stars
Halo: old stars
How can we distinguish halo stars passing
through the disk of the galaxy from disk
stars?
By studying the motion and composition of the stars.
Halo stars are metal poor, old stars and travel in
rather random orbital orientations. Disk stars are
younger, more metal rich and orbit in the same
orientation, excepting some up and down motion
A Quasar is an example of a(n)
Active galactic nuclei
The luminosity of an AGN (active galactic
nuclei) can exceed _______.
One trillion times the
luminosity
of the Sun (1012 LSun)
AGN vary rapidly. This
means that they are
located within a region of a
host galaxy which is
________
Very small (in fact within a space smaller
than the Solar System!)
Quasars have a very large redshift this
means that ___________.
1) They are generally
very distant
2) They were more
common early in time
3) Galaxy collisions
might turn them on
4)Nearby galaxies might
hold dead quasars
The source of AGN light is
____________
Accretion of gas onto a supermassive black
hole
The source of the radio
wave signals in radio
galaxies is/are
__________.
Vast jets of plasma, with electrons moving
close to the speed of light
Why don’t all AGN appear
the same?
Viewing orientation
Blazar
Quasar or
Seyfert Galaxy
Radio
Galaxy
E0 galaxies are more
_______ than E7 galaxies
Spherical
Starburst galaxies are so
called because
_________.
They are experiencing a period of rapid star
formation
Name one difference
between a Sa and a Sc
type galaxy
In Sa galaxies, the arms
are tighter and the bulge is
more prominent
Between elliptical and
spiral galaxies, which is
more likely to have young
stars, and gas?
Spiral galaxies
What is a lenticular
galaxy?
A galaxy with a disk and
prominent bulge but with
no obvious spiral arms.
Although they can have
dust, they have little gas
and do not have much star
formation and are mostly
older stars
Between elliptical and
spiral galaxies, which is
more likely to have young
stars, and gas?
Spiral galaxies
Where in a spiral galaxy
would you most likely find
globular clusters?
The halo
Are galaxy collisions more
common now than in the
past?
No! They were more
common in the past, when
the Universe was denser
and galaxies were
generally closer together
What type of galaxy will
result from the collision of
Andromeda and the Milky
Way?
An elliptical galaxy
Why do galaxy mergers
result in increased star
formation?
Because gas clouds collide
which increases the
density of these clouds
and then triggers star
formation
Why does dark matter
remain in a halo around
galaxies during galaxy
formation?
Because it cannot radiate
away energy
In what way does density
of a protogalactic cloud
determine whether a
galaxy formed into a spiral
or an elliptical galaxy?
Elliptical galaxies come
from denser clouds that
cool and form stars before
the gas is able to settle
into a disk
What does it mean that
fragmentation in galaxy
formation is a bottom-up
mechanism?
It means that smaller
structures collapse first
and then merge to make a
bigger structures.
How did supernovae
explosions of the first stars
contribute to the formation
of disks in galaxies?
The explosions prevented
gas from forming more
stars. This gas was able to
settle into a spinning disk
via conservation of angular
momentum
How are Cepheids used to
measure the distances to
nearby galaxies?
Using Leavitt’s Law which
shows that the period of a
Cepheid is related to its
luminosity
How is the Tully-Fisher
relationship used to
measure distances to
galaxies?
Astronomers measure the
rotation speed of stars in
the galaxy using
spectroscopy (the Doppler
effect). This is related to
the luminosity of the
galaxy,
What is the cosmological
principal?
The Universe looks the
same everywhere.
This means that expansion
looks the same to all
observers and the universe
has no center or edges
How is Hubble’s Law used
to get distances to distant
galaxies?
Astronomer’s measure the
recessional velocity
(moving away from us) of
the galaxy. This is related
to distance by: V=H0* D.
Do all galaxies show
recessional redshift?
No! Distant galaxies do
because of the expansion
of the Universe but some
nearby galaxies are
moving toward the Milky
Way and these show blue
shifts.
What is lookback time?
The time it took the light of
an object to reach us.
Because light travels at a
finite speed, this means we
are looking at these
objects in their past.
Why can’t we use parallax
to measure distances to
galaxies?
Because parallax is
inverse to distance, this
means that objects at very
big distances show small
parallaxes. We can’t detect
the change!
How do astronomers know
that the Milky Way has a
supermassive black hole in
its center?
The orbits of stars close to
the center of the Milky Way
suggest a very massive an
object in a very small area.
What is the upper mass
limit for a supermassive
black hole?
Roughly 50 billion solar
masses
What does the presence of
quasars in the early
Universe suggest about
supermassive black holes?
That even in the first
massive galaxies,
supermassive black holes
were present. Thus they
formed early in the history
of the Universe
What does the fact that the
mass of a galaxy’s central
black hole is related to the
mass of the bulge of a
galaxy suggest?
That the development and
growth of the
supermassive black hole is
related to galaxy evolution
What is the M-sigma
relation?
The relation between the
stellar velocity dispersion
(sigma) in the bulge of a
galaxy and the mass of its
supermassive black hole.
Galaxies with higher
sigma, have a more
massive central black hole
If you want to look toward
the center of the Milky Way
and its supermassive black
hole, which constellation
should you look at?
Sagittarius
If AGN are evidence that
galaxies have
supermassive black holes
and the Milky Way has a
supermassive black hole,
then why isn’t it an AGN?
Because the Milky Way’s
supermassive black hole is
not currently “consuming”
enough material and
probably lacks a large
enough accretion disk