Quiz 6 Flashcards
About 380,000 years after the big bang
Matter and radiation decoupled
The radio emission seen from a typical radio galaxy
Comes from its radio lobes
What do we call galaxies that seem to have the nuclear bulge and disk of a spiral but no arms?
Lenticular
The steady state theory is a real theory
True
According to the density wave theory, star formation would be seen
on the inside edge of a spiral arm
The large flat part of a galaxy that rotates in a plane around its center
disk
We cannot use star counting in the Galactic disk in order to locate its center because
we cannot observe stars in the disk except in our vicinity due to the effects of interstellar dust on starlight
Gravitational lenses
All of the above
Hubble constant gives us an approximate age of the universe of
12-15 billion years
The local group of galaxies is a cluster of over _____ galaxies that includes the Milky Way Galaxy, the Andromeda galaxy, the two magellanic clouds, and numerous dwarf galaxies
54
Olbers’ paradox is an argument showing that he sky in an infinite, static universe could not be dark
True
Which of the following is true about the amounts of heavy chemical elements in the early universe
They were insignificant
The small fluctuations that are observed in the CMB radiation are significant because
They show that the early universe was not completely homogeneous
When we talk about “isotropy” in cosmology we mean that
The universe looks the same in any direction
Dark energy (whatever it turns out to be) is slowing the expansion of the universe
False
How many billions of stars are in the Milky Way Galaxy?
200
What percentage of the universe is made up of Cold Dark Matter?
20
Hubble divided spiral galaxies into two groups: ordinary spirals and ______ spirals.
Barred
Most of the galaxies in existence are elliptical
True
The Milky Way Galaxy is which type of galaxy?
Spiral
We say that quasars, blazars and radio galaxies are really the same thing because
We can explain observations of these objects with a single model
Observations show that clusters of galaxies are filled with
high temperature, low density gas
Population II stars in our Galaxy are found mostly
in globular clusters
According to the self-propagating star formation theory of galactic arms, the triggers that start the collapse of most interstellar clouds are nearby black holes
False
Newton proposed that the universe was infinite because if it were not, gravity would cause it to collapse to its center
True
