Types of Galaxies

Our Milky Way Galaxy is what type of galaxy?

• spiral
• elliptical
• dwarf elliptical
• irregular

Which type of galaxy is observed to contain mostly older stars?

• spiral
• elliptical
• dwarf elliptical
• irregular
• none of the above

Which of the following is NOT a characteristic of a spiral galaxy?

• most of its material is in the shape of a flattened disk
• it has quite a bit of gas and dust in it
• it has young stars and bright emission nebulae
• when we take spectra of its stars, they have far less of the heavier elements than the Sun
• the bright stars in it can be seen organized into distinct spiral arms

About two thirds of the nearby spiral galaxies (which we can study in more detail) don’t have a round central bulge, but instead show

• no central bulge at all, just a uniform galaxy
• a central bulge with a bar of stars in the middle
• a central bulge with a completely irregular and unsymmetric shape
• a central bulge with 2 giant jets coming out larger than the galaxy
• you can’t fool me; all spirals have a round central bulge

The type of galaxy that sometimes has a distinct bar of stars running across the central region is

• spiral
• elliptical
• dwarf elliptical
• irregular
• all of the above can have clear, distinct central bars

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

• their brightness
• their overall color
• their shape
• their abundance of the element iron
• their Doppler Shift

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:

• spiral
• elliptical
• irregular
• barred spiral
• all of the above consist almost entirely of old stars

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

• spiral
• elliptical
• dwarf elliptical
• irregular
• none of the above

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
• they are among the biggest irregular galaxies ever found
• they have a regular shape, but it is so complicated it was hard to figure out
• they do not contain any young stars at all, only really old ones
• their shape resembles a map of Bayonne, New Jersey

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?

• determine whether or not there is evidence for a massive black hole at the galaxy's center
• construct an H-R diagram for a prominent open cluster in the galaxy's disk
• measure the gamma-ray emission from the galaxy
• compare the overall color of the galaxy to other galaxies of the same type
• obtain the speed at which stars or gas near the outer regions of the galaxy are moving around

Tags

NGSS.HS-PS2-1