HW 14 - Ch 26 & 28

Which of the following was not done by Edwin Hubble?

discovering the relationship between period and luminosity of a cepheid variable

If a galaxy contains a great deal of "dark matter," what will that do the galaxy's mass-to-light ratio?

increase it quite a bit

Which of the following is a way that having an active galactic nucleus (AGN), with a supermassive black hole in the center, can affect the development of a galaxy?

it can cut off all electro-magnetic radiation from most of the galaxy, except for the visible light from the outermost stars

Edwin Hubble developed a classification scheme for galaxies. By what characteristic did he classify galaxies?

their shape

Which of the following can we Not learn from studying the Doppler shifts in the spectrum of galaxies beyond our Local Group?

whether they have Jupiter-mass planets around many of their stars

How do astronomers know that there aren't significant amounts of dark matter within our solar system?

a lot of dark matter would affect the motions (orbits) of our spacecraft as the move through the solar system, and see no such effect

By examining rich clusters of galaxies, such as the Coma Clusters, astronomers have discovered that spiral galaxies

are found mostly in the outer regions of such clusters, not in the middle

When astronomers have examined rich clusters of galaxies with their instruments, they have found that these clusters

are more likely to contain giant elliptical galaxies than poor clusters

Which type of galaxy is very difficult to see, but (astronomers recently realized) may be very common?

dwarf elliptical

The type of galaxy that consists almost entirely of old stars and is thus less blue (more yellow and reddish) than the other types is:

elliptical

What do the surveys of the three-dimensional distribution of groups of galaxies reveal about how groups and clusters of galaxies are organized?

galaxy groups make a huge spiral structure that resembles the Milky Way (but is much bigger)

If we want to see what galaxies looked like at a time close to the beginning of the universe, where should we look?

in a direction away from the plane of the Milky Way, where we can see very faint galaxies that are more than 10 billion light years away

If a galaxy contains a great deal of dark matter, then, compared to the mass-to-light ratio of the inner part, the mass-to-light ratio of the whole galaxy will be

more

According to Hubble's Law, if two galaxies are not part of our Local Group, and galaxy B is three times farther away from us as Galaxy A, then Galaxy B will

move away from us three times faster than A

An astronomer is observing a distant galaxy which looks blue. Which of the following can she conclude from this observation?

the galaxy must have a lot of star formation going on at the time we are seeing it

Among irregular galaxies, what makes the Large and Small Magellanic Cloud especially useful for astronomers?

they are (for galaxies) very close to us, so they are easy to study

The reason type Ia supernovae are useful to astronomers for determining distances to other galaxies is that

they are very bright, and generally reach the same peak luminosity

One important way astronomers can learn in some detail about what happens when galaxies collide is

to simulate galaxy collisions on a large computer and watch what the simulation predicts

The "great voids" that astronomers studying galaxies are finding are:

very large regions of intergalactic space, where relatively few galaxies or galaxy clusters can be found

Before you can use Hubble's Law to get the distance to a galaxy, what observation must you make of that galaxy?

you must take a spectrum of the galaxy and measure the red shift