Exam 21: The Milky Waya Normal Spiral Galaxy

By comparing globular clusters,you find that Cluster A's RR Lyrae stars are 225 times fainter than Cluster B's RR Lyrae stars.You know that both clusters have approximately the same chemical composition and age,and thus their RR Lyrae stars should have the same luminosities.Which cluster has the larger distance,and what is the ratio of the clusters' distances?

The Sun is located approximately:

Below are two images of the Milky Way at different wavelengths.Which one was taken at infrared wavelengths,and why do you think so?

Explain how a standard candle allows you to determine the distance to an object.What is it that you have to measure or know about the standard candle to derive its distance?

The ratio of the diameter of the galaxy's disk to the thickness of its disk is about:

In the Milky Way's outermost halo,the stars orbit:

What is ripping apart the Sagittarius dwarf spheroidal galaxy?

Describe a scale model of the disk of the Milky Way using a scale in which 1 cm = 1000 light-years.Note that the diameter of the disk is approximately 100,000 light-years,the thickness of young stars is 500 light-years,and the thickness of the older stars is 4,000 light-years.

Why do we know that at least one generation of stars formed and died before the Milky Way's globular clusters formed?

We find that interstellar gas and the youngest disk stars are found in a very narrow distribution along the galactic plane,but that older disk stars can be found in a thicker disk.What might this mean?

What is the radius of the event horizon for the 4 × 10⁶ M_⨀ black hole at the center of the Milky Way?

Globular clusters,when compared to open clusters,generally:

Most of the gravity that the Sun feels in the galaxy is caused by the black hole at the center of the Milky Way.

Cosmic rays in the Milky Way are important because:

If you wanted to study the properties of nearby stars that were some of the first stars to form in the Milky Way,but were NOT members of a globular cluster,how could you go about finding them?

By comparing globular clusters,you find that Cluster A's RR Lyrae stars are 100 times fainter than Cluster B's RR Lyrae stars.You know that both clusters have approximately the same chemical composition and age,and thus their RR Lyrae stars should have the same luminosities.Which is true about the clusters' distances?

If the Large Magellanic Cloud is orbiting the Milky Way in a circular orbit with a speed of 175 km/s and a distance of 50 kpc from the center,how long would it take for the Large Magellanic Cloud to complete one orbit around the Milky Way?

Globular clusters are found in which stellar subgroups of the galaxy?

Our galaxy is __________ other galaxies because the dark matter in the Milky Way __________.

The location and motions of interstellar gas can be strongly affected by what?