Ch. 11c Doubles, Variables, and Clusters

Castor (alpha Geminorum) is a triple visual binary. Each component is also a spectroscopic binary. How many stars are part of Castor?
1. 1
2. 2
3. 3
4. 6
Why can we learn about stars that are in binary systems that we cannot learn about stars that are not part of binary systems?
1. the mass of the stars
2. the apparent magnitude of the stars
3. the temperatures of the stars
4. the composition of the stars
The light curve of a Cepheid variable star is shown here.
What is the maximum apparent magnitude of the star?
1. 3.6
2. 4.3
3. 3.95
4. 6
The light curve of a Cepheid variable star is shown here.
What is the minimum apparent magnitude of the star?
1. 3.6
2. 4.3
3. 3.95
4. 6
The light curve of a Cepheid variable star is shown here.
What is the average apparent magnitude of the star?
1. 3.6
2. 4.3
3. 3.95
4. 6
The light curve of a Cepheid variable star is shown here.
What is the period of the star? Include units.
1. 3 days
2. 6 days
3. 7 days
4. 13 days
The period-luminosity relation for Cepheid variables is shown.
What is the absolute magnitude of a Cepheid variable that has a period of 10 days?
1. -3
2. -5
3. 3 days
4. 10 days
The period-luminosity relation for Cepheid variables is shown.
What is the absolute magnitude of a Cepheid variable that has a period of 3 days?
1. -2
2. -3
3. -4
4. 10 days
The period-luminosity relation for Cepheid variables is shown.
What is the period of a Cepheid variable star that has an absolute magnitude of -4? Include units.
1. 30 days
2. -2.5
3. 10 days
4. 3 days
The light curve of a Cepheid variable star is shown here.
The period-luminosity relation for Cepheid variables is also shown.
What is the absolute magnitude of this star?
1. 6 days
2. -2.5
3. 4.3
4. 3.6
Why are Cepheid variable stars important to astronomers?
1. They can be used to determine distance.
2. They allow astronomers to determine the time between supernova outbusts.
3. Cepheid variables are the smallest of all stars.
4. You can’t fool me; Cepheid variable stars are not important to astronomers.
What type of cluster is shown here?
1. globular cluster
2. open cluster
What type of cluster is shown here?
1. globular cluster
2. open cluster
The light curves of two variable stars are shown here.
Which one represents a Cepheid variable star?
1. red
2. blue
3. both curves show Cepheid variable stars
4. neither curve shows a Cepheid variable
H-R diagrams of two different galactic clusters are shown here.
Which cluster is older?
1. top
2. bottom
3. both clusters are the same age
4. cluster ages can not be determined
H-R diagrams of two different galactic clusters are shown here.
How would these cluster appear visually different from one another?
1. Cluster “Top” has curving stars; cluster “Bottom” has a straighter shape.
2. Cluster “Top” doesn’t have any blue stars in it; cluster “Bottom” does have blue stars in it.
3. Galactic clusters all look the same in every way.
4. The appearence of a cluster can not be determined from an HR diagram.
How are Open Clusters with Galactic Clusters similar?
1. They are the same thing.
2. They both have only old stars.
3. The mass of the stars in them can be determined.
4. They are in no way similar.
How are Open Clusters and Globular Clusters different?
1. Open Clusters usually have only older stars. Globular Clusters can have much younger stars.
2. Globular Clusters usually have only older stars. Open Clusters can have much younger stars.
How are Open Clusters and Globular Clusters different?
1. Open Clusters usually have a lot more stars and are much larger than Globular Clusters.
2. Globular Clusters usually have a lot more stars and are much larger than Open Clusters.
How are Open Clusters and Globular Clusters different?
1. Open Clusters are found in the galactic disk while Globular Clusters are found in th e halo of the glaxies.
2. Globular Clusters are found in the galactic disk while Open Clusters are found in th e halo of the glaxies.
The size of a single star can be determined if we know its absolute magnitude and its
1. distance.
2. temperature.
3. proper motion.
4. radial velocity.
A star which appears double when observed directly, and is held together by mutual gravitation is called a(n)
1. spectroscopic binary.
2. optical double.
3. visual binary.
4. eclipsing binary.
A binary star which varies in brightness as one component passes in front of the other is a(n)
1. spectroscopic binary.
2. optical double.
3. visual binary.
4. eclipsing binary.
The main value in the study of binary stars is the ability it gives us to determine stellar
1. colors.
2. masses.
3. periods.
4. sizes.
Common red giant variable stars such as Mira that vary slowly in brightness are called
1. Cepheid variables.
2. eclipsing binaries.
3. long-period variables.
4. RR Lyrae variables.
The period-luminosity relation that Henrietta Leavitt discovered applies to
1. Cepheid variables.
2. eclipsing binaries.
3. Mira variables.
4. RR Lyrae variables.
Variable stars with very short regular periods, found mainly in clusters, are
1. Cepheid variables.
2. Mira variables.
3. eclipsing binaries.
4. RR Lyrae variables.
Star clusters with irregular shapes, and containing relatively young stars, are called
1. globular clusters.
2. open clusters.
3. halo clusters.
4. New Population clusters.
Star clusters made of many thousands of older stars are called
1. globular clusters.
2. Population I areas.
3. open clusters.
4. Population II areas.
The age of an open cluster can be determined from its
1. color.
2. horizontal branch.
3. temperature-luminosity (HR) diagram.
4. number of Population II stars.

Ch. 11c Doubles, Variables, and Clusters

Review Questions