Ch. 26 Galaxies

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: a. spiral b. elliptical c. irregular d. barred spiral e. all of the above consist almost entirely of old stars

b. elliptical

Our Milky Way is what type of galaxy? a. spiral b. elliptical c. dwarf elliptical d. irregular e. giant elliptical

a. spiral

The type of galaxy that sometimes has a distinct bar of stars running across the central region is a. spiral b. elliptical c. dwarf elliptical d. irregular e. all of the above can have clear, distinct central bars

a. spiral

One of the most important observations in the history of astronomy was the one by Edwin Hubble that established that there are other galaxies, quite removed from the Milky Way. How did Hubble show this? a. by debating with Harlow Shapley and being more eloquent b. by observing a supernova explosion in a nearby galaxy, using it as a "standard bulb" c. by observing a Cepheid variable in a nearby galaxy and using it to get the distance d. by measuring the distances to many globular clusters using parallax e. by going to see Einstein, who knew the answers to these kinds of questions

c. by observing a Cepheid variable in a nearby galaxy and using it to get the distance

Among irregular galaxies, what makes the Large and Small Magellanic Cloud especially useful for astronomers? a. they are (for galaxies) very close to us, so they are easy to study b. they are among the biggest irregular galaxies ever found c. they have a regular shape, but it is so complicated it was hard to figure out d. they do not contain any young stars at all, only really old ones e. their shape resembles a map of Bayonne, New Jersey

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

Which type of galaxy is very difficult to see, but (astronomers recently realized) may be very common? a. spiral b. elliptical c. dwarf elliptical d. irregular e. none of the above

c. dwarf elliptical

Which is one reason that the typical galaxy's mass-to-light ratio (in units of the Sun's mass over the Sun's luminosity) generally greater than 1? a. galaxies contain mostly stars much brighter than the Sun b. galaxies contain mostly stars much more massive than the Sun c. galaxies contain many more stars that shine much less brightly than the Sun d. most of the mass in a galaxy is in the form of dust e. this is an unsolved problem in astronomy; scientists have no clue

c. galaxies contain many more stars that shine much less brightly than the Sun

Edwin Hubble developed a classification scheme for galaxies. By what characteristic did he classify galaxies? a. their brightness b. their overall color c. their shape d. their abundance of the element iron e. their Doppler Shift

c. their shape

About two thirds of the nearby spiral galaxies (which we can study in more detail) don't have a round central budge, but instead show a. no central bulge at all, just a uniform galaxy b. a central bulge with a bar of stars in the middle c. a central bulge with a completely irregular and unsymmetric shape d. a central bulge with 2 giant jets coming out larger than the galaxy e. you can't fool me; all spirals have a round central bulge

b. a central budge with a bar of stars in the middle

Which type of galaxy is observed to contain mostly older stars? a. spiral b. elliptical c. dwarf elliptical d. irregular e. none of the above

b. elliptical

Which of the following statements about the different types (shapes) of galaxies is correct? a. whatever type a galaxy is at its birth, that's what it will be for all time b. all galaxies start out as ellipticals, but some later evolve to be spirals and irregulars c. 90% of all galaxies are spirals (including our Milky Way); the other two types are very unusual d. collisions and mergers between galaxies can sometimes change a galaxy's type (shape) e. what type we see a galaxy to be just depends on the angle at which we happen to see it; all galaxies look roughly the same in shape

d. collisions and mergers between galaxies can sometimes change a galaxy's type (shape)

Compared to the mass of our own Milky Way, the total mass we estimate for the Andromeda Galaxy is a. a lot smaller b. a little bit smaller c. exactly the same d. somewhat bigger e. not something we can measure

d. somewhat bigger

The new instrument that made it possible for Edwin Hubble to demonstrate the existence of other galaxies in the early 1920s was: a. the Hubble Space Telescope (that's why we named it after Hubble!) b. the 300-ft radio telescope in West Virginia c. a kind of electronic detector called a CCD d. the 100-inch reflector on Mount Wilson e. an infra-red telescope carried aboard one of the early airplane flights by the Wright Brothers

d. the 100-inch reflector on Mount Wilson

Which of the following is NOT a characteristic of a spiral galaxy? a. most of its material is in the shape of a flattened disk b. it has quite a bit of gas and dust in it c. it has young stars and bright emission nebulae d. when we take spectra of its stars, they have far less of the heavier elements than the Sun e. the bright stars in it can be seen organized into distinct spiral arms

d. when we take spectra of its stars, they have far less of the heavier elements than the Sun

A graduate student in astronomy needs to measure the mass of a spiral galaxy she is studying for her PhD thesis. Which of the following observations would be important for her to make? a. determine whether or not there is evidence for a massive black hole at the galaxy's center b. construct an H-R diagram for a prominent open cluster in the galaxy's disk c. measure the gamma-ray emission from the galaxy d. compare the overall color of the galaxy to other galaxies of the same type e. obtain the speed at which stars or gas near the outer regions of the galaxy are moving around

e. obtain the speed at which stars or gas near the outer regions of the galaxy are moving around