Examine the hypothetical stars listed below. Refer to these stars in answering the following questions.

Star m M DistanceParsecs

SpectralType

Luminosity Class

A 11.05 15.5 1.3 M5 VB 0.91 -3.6 80 B1 VC -0.3 -0.3 10 K2 IIID 1.79 -6.8 491 O9 IE 1.26 -6.9 429 A2 I

1. Which of the stars listed above is appears the dimmest?A B C D E

2. Which of the stars listed above is the most luminous?A B C D E

3. Which of the stars listed above is the hottest?A B C D E

4. Which of the stars listed above is the largest in radius?A B C D E

5. Which of the stars listed above is the closest?A B C D E

6. Which of the stars listed above is 10 parsecs away?A B C D E

7. Which of the stars listed above is a main sequence star?A B C D E

8. Which of the two stars D or E is closer?A B C D E

The questions below refer to the HR diagram on the next page. 9. Which of the lettered stars on the HR diagram is most like the Sun?

A B C D E

10. Which of the lettered stars on the HR diagram is least likely to be one of the bright stars you see at night?

A B C D E

11. Which of the lettered stars would be a blue supergiant?A B C D E

12. Which of the lettered stars on the HR diagram is about 100 times more luminous than the Sun?

A B C D E

13. Briefly describe what changes in temperature and radius must occur to Star C to transform it into Star E?

14. Briefly describe what changes in temperature and radius must occur to Star E to transform it into Star A?

15. Image that you are the star labeled Star D. Tell me about yourself. Describe your physical characteristics and any noteworthy features or properties you possess.

16. The original form of the Sun’s luminosity is in deadly gamma rays. Please explain why we are not harmed by those gamma rays.

NOTE: The HR diagram the questions above refer to is NOT shown.

17. The HR Diagrams for two open clusters are shown below. Please identify which Open Cluster is the oldest and justify your choice using your knowledge of stellar evolution.

18. There are reported to be about 6,000 stars visible to the naked eye. How many of those stars would you expect to be part of a multiple star system?

AnswerEssay Questions

19. The Sun has a limited lifetime. In the space below, please justify this statement by detailing the process of energy generation in the Sun and describing why the Sun has a limited lifetime.

20. I have heard it said that the Sun is a “typical” star in the Milky Way galaxy. Please make an argument below citing specific characteristics of the Sun and the most common types of stars in the Milky Way galaxy to either support or refute this statement.

Answer all questions on the exam in the provided spaces. Use the Scantron answer sheet to record your answers.Refer to these stars in the table below in answering the following questions. There may be more than one correct answer to some of the following questions. Choose all that apply.

Star m M SpectralType

Luminosity Class

A 1.29 -5.2 A2 IIB 0.91 -3.6 B1 VC 11.05 15.5 M5 V

D 1.36 -6.8 O9 IE -0.3 -0.3 K2 III

1) Which of the stars listed above is appears the dimmest?

2) Which of the stars listed above is the most luminous?

3) Which of the stars listed above is the hottest?

4) Which of the stars listed above is the largest in radius?

5) Which of the stars listed above is the closest?

6) Which of the stars listed above is 10 parsecs away?

7) Which of the stars listed above is a main sequence star?

8) Which of the two stars D or E is closer?

9) Which of the stars listed above has the longest remaining lifetime?

10) Which of the stars listed above has a spectral type different from its original spectral type?

The HR Diagram at right is provided to assist with answering the following two questions.

11) Which is hotter, a main sequence star with an absolute magnitude of M= 4 or a white dwarf with a luminosity 100 times smaller than the Sun?A) the main sequence starB) the white dwarfC) They have the same temperature.D) There is insufficient information

to determine this.

12) Which statement is the most correct about the comparison between a K5 main sequence star and a B5 main sequence star?A) The K5 star is cooler, less

luminous, smaller, and will not live as long as the B5 main sequence star.

B) The K5 star is hotter, less luminous, larger, and will live longer than the B5 main sequence star.

C) The K5 star is smaller, hotter, more luminous, and will not live as long as the B5 main sequence star.

D) The K5 star is hotter, more luminous, smaller, and will live longer than the B5 main sequence star.

E) The K5 star is less luminous, cooler, smaller, and will live longer than the B5 main sequence star.

This is a” thinking” question: Star A appears brighter than Star B, but Star A actually gives off less energy than Star B. The apparent magnitude and absolute magnitudes for Star A are m = 1 and M = -2, respectively. Use this information to answer the following two questions.

13) Which of the following are the best possible values for the apparent and absolute magnitudes of Star B?A) m = -1 and M = 2B) m = -1 and M = -4

C) m = 3 and M = 2D) m = 3 and M = -4

14) Which is the most correct statement about the distance of Star A from Earth?A) Star A is closer than 10 pc from Earth.B) Star A is exactly 10 pc from Earth.C) Star A is farther than 10 pc from Earth.

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c

e

Temperature (K)

Lum

inos

ity (s

olar

uni

ts)

Spectral Type

Absolute m

agnitude

20,000 10,000 5,000

O5 B5 A5 F5 G5 K5 M5

10,000

1,000

100

10

1

.1

.01

.001

.0001

a

b

d

f

-5

0

5

10

15

Main Sequence

Red Giants

White Dwarfs

Imagine you are comparing the five stars (A-E, shown below) of different radii and temperatures. The temperature of each star is indicated by a shade of gray (as shown at right), such that the lighter the shade of gray, the higher the temperature of the star.

15) Which of the following is the most correct ranking for the luminosity of these stars from greatest to least?

A) C > E > A >B > DB) D > B > A >E > C

C) C > E > B >A > DD) E > C> A >B > D

E) C = E > A =B > D

16) How does the Sun produce the energy that heats our planet?A) The gases inside the Sun are burning and producing large amounts of energy.B) Hydrogen is combined into helium, giving off large amounts of energy.C) Gas inside the Sun heats up when compressed, giving off large amounts of energy.D) Heat trapped by magnetic fields in the Sun is released as energy.E) The core of the Sun has radioactive atoms that give off energy as they decay.

17) If the stars Betelgeuse and Rigel were to have the same luminosity but the temperature of Betelgeuse is cooler than Rigel, which star has the greater surface area?A) BetelgeuseB) RigelC) They are the same size.

D) There is insufficient information to answer this question.

High

Medium

LowA B C D E

Use the four HR diagrams shown below to answer the following two questions.

29) Which of the following is the most correct ranking for the age of the star clusters from youngest to oldest?A) A<B<C<DB) D<C<A<B

C) C<B<A<DD) D<A<B<C

30) Which of the star clusters in the HR diagrams has a large number of stars that are producing energy by core He-burning?A) Star Cluster AB) Star Cluster B

C) Star Cluster CD) Star Cluster D

Star Cluster C

Star Cluster A

Star Cluster D

Star Cluster B

32) Proxima Centauri is a main sequence star that appears red when viewed from Earth, as a result which of the following are true: A) It is hotter than an O spectral class main sequence star. B) It is moving toward the Earth.C) It is moving away from the Earth.D) It will live longer than a B spectral class main sequence star.E) It is the same size as a red giant star of the same temperature.