Physics 112                                                     Name_______________________________

Astronomy

Dr. Kolan

 

FINAL EXAM

May 20, 2003

 

I pledge my honor that during this examination I have neither given nor received assistance, and that I have seen no dishonest work.

Signed________________________________

 

I have intentionally not signed the pledge.__________________________

 

There are 110 points possible on this exam.

 

 

Identify the object.  (2 points apiece)

 

1)    I'm the galaxy we live in.

 

 

2)    I'm a rotating neutron star with a very strong magnetic field.  Interactions between charged particles and my magnetic field produce a beam of electromagnetic radiation that is bright in the X-ray, visible, and radio portions of the spectrum.

 

 

3)    I am one of the Galilean moons.  My surface is distinctive in that it is pock marked with sulfur volcanoes.

 

 

4)    I have a temperature of 11,820o K, a diameter slight larger than the earth's, a mass of .69 Msun, and an average density of 6 tons per cubic feet.

 

 

5)    I'm the point in the sky about which all stars appear to revolve over the course of the night.

 

 

6)    I'm the apparent shift in position of a star against its background due to the motion of the observer.

 

 

7)    I'm a bright pulsating star that is very important in determining distances to galaxies.

 

 

8)    I'm the plane of the earth's rotation about the sun.  I'm also an imaginary line passing through the zodiac constellations.

 

 

9)    I'm a star that is converting hydrogen to helium in its core.

 

 

10) I'm the process whereby hydrogen is converted to helium in the core of a star.

 

 

 

 

Short Answer.  (10 points apiece)

 

1)    The May 2003 issue of Astronomy magazine has an article entitled "Eclipse Extravaganza".  The promo for the article reads "May offers a double dose for eclipse watchers, with a total lunar eclipse followed by an annular eclipse two weeks later".  Is it unusual to have eclipses separated by a two week interval?  Why or why not?

 

 

 

 

 

 

 

 

2)    The Tully-Fisher relationship states that the faster a galaxy rotates the more luminous the galaxy.  Explain why this relationship makes sense in terms of Kepler's third law.  Explain why the Tully-Fisher relationship is important to astronomers.

 

 

 

 

 

 

 

 

 

3)    The Hubble telescope has recently been used to view very distant galaxies in the infrared.  Why is it preferable to view these galaxies in the infrared instead of the visible?

 

 

 

 

 

 

4)    How (and why) does a stellar spectrum give you information on the temperature of a star?

 

 

 

 

 

 

 

 

 

 

 

5)    What's the difference between dark matter and dark energy?

 

 

 

 

 

 

 

Of the following short answers, pick 5 of the 9 questions to answer.  Make sure that you indicate which questions you want graded (otherwise I will just grade the first 5 questions that you have answered).  (10 points apiece)

 

 

6)    In the May 2003 issue of Astronomy is an article on extrasolar planets.  It states the "like the sun, other stars harboring planets are richer in elements heavier than helium (metals, to astronomers) than the overall stellar population".  Why would one star be metal rich and another metal poor?

 

 

 

 

 

 

 

 

7)    According to an article in the April 2002 issue of Astronomy, "legend has it that the great Polish astronomer Copernicus never saw the planet Mercury".  Who was Copernicus?  Why is Mercury hard to view?

 

 

 

 

8)    The April 2003 issue of Astronomy has an article entitled "Night-vision satellite".  It states "astronomers are most familiar with the DMSP (the U.S. Air Force Defense Meteorological Satellite Program) from its sensational mosaics of Earth at night that show light and light pollution from cities, fires, fishing boats, and even volcanoes.  While these images make great wall hangings, the DMSP's primary mission is not to provide pretty posters.  Instead, the DMSP is used to monitor forest fires, changes in population density via light density, and also track clouds at night.  The military also uses the DMSP to monitor the efficiency of nighttime bombing raids and to track nighttime enemy/terrorist movements".  What form of electromagnetic radiation does the DMSP "see"? (Hint--it's not visible light).  Support your answer.

 

 

 

 

 

 

 

 

9)    Explain how the equivalence principle implies that light bends in a gravitational field.  Give an astronomical example of light bending near a massive object.

 

 

 

 

 

 

 

 

10) We have encountered three different red shifts in this class.  Give the names of the three redshifts and a brief description of each.

 

 

 

 

 

 

 

 

11) Why are white dwarf supernovae important to astronomers?

 

 

 

 

 

 

 

 

12) What is Olber's paradox?  What is the resolution of Olber's paradox?

 

 

 

 

 

 

 

 

13) We have talked about Messier objects in class--these are fuzzy objects that could be mistaken for comets.  We now know that Messier objects are a variety of astronomical objects.  What are three different types of astronomical objects that are found in the Messier catalog?

 

 

 

 

 

 

 

 

14) What's the difference between a blackbody and a black hole?

 

 

 

 

 

 

 

 

 

 

Have a Great Summer Break!  I enjoyed having you in class.