Astronomy Test Ch 23 & 24

The part of the Milky Way we are most familiar with is the:

• Corona

• Galactic Disk

• Halo

• Galactic Bulge

• Galactic Center

 What perception of the Milky Way Galaxy did astronomers have in 1900?

• They believed that the Earth rested inside concentric spheres, with the Milky Way stars fixed to the outermost sphere.

• They believed that the Milky Way was one of billions of galaxies in the universe.

• They believed that the Milky Way was the entire universe.

• They believed that, because the Sun was at the center of the Milky Way, it was impossible to  see the rest of the universe.

•  They believed we were one of billions galaxies in an expanding universe.

What is one of the differences between Cepheid variables and RR Lyrae variables?

• Cepheids are higher luminosity stars than RR Lyrae variables, and have longer periods.

• All Cepheids have the same luminosity, while RR Lyrae stars vary greatly in brightness.

• RR Lyrae variables pulsate irregularly as compared to Cepheids which are very regular.

• RR Lyrae are eclipsing binaries, but Cepheids actually do pulsate.

• Cepheids vary because they are mass transfer binaries; RR Lyrae variables vary because they are pulsating single stars.

The location of the center of the Galaxy was determined by Shapley from observations of:

• cepheids in open clusters.

• RR Lyrae variables in globular clusters.

• Herbig-Haro objects in emission nebulae.

• blue supergiants in the spiral arms.

• the radio emissions from Sagittarius A.

 Where is our Sun located in the Milky Way Galaxy?

• at the exact center

• near the center

• about halfway between the center and the outer edge

• near the outer edge

The first attempt to map the Galaxy via star counts was done by:

• Galileo in 1612.

• William Herschel in the late eighteenth century.

• Edward Barnard with long exposure photos about 1900.

•  Harlow Shapley with the RR Lyrae variables in 1920.

• Edwin Hubble with the new 100" Mt. Wilson telescope in the 1930s.

It was the distribution of ________ that showed Harlow Shapley we were no where near the center of the Milky Way in the 1920s.

• planetary nebulae

• emission nebulae

• open clusters

• globular clusters

• supernova remnants

  The man who almost singlehandedly made the Milky Way five times larger in the 1920s was:

• Edwin Hubble

• Heber Curtiss

• William Herschel

• Edward Barnard

• Harlow Shapley

Which of the following structures is not a part of our own Milky Way Galaxy?

• halo

• nucleus

• disk

• ring

• spiral arms

 Which sequence of formation by age is correct, oldest to youngest?

• dark nebulae, planetary nebulae, emission nebulae

• spiral arms, bulge, halo

• halo, spiral arms, globular clusters

•  globular clusters,  emission nebulae, open clusters

• Population I stars, Population II stars, Population III stars