astronomy questions with answers

Nevada State Science Olympiad Astronomy Division Event

6 March 2010 Rancho High SchoolLas Vegas, Nevada

TEAM/SCHOOL NAME: ____________________________________________

TEAM MEMBERS:________________________________________________

INSTRUCTIONS:

1. Attempt to answer all questions. There is no additional penalty for wrong answers.

2. Please turn in ALL MATERIALS at the end of this event.

3. Do not forget to put your TEAM NAME and TEAM NUMBER at the top of all Answer Pages.

4. Good Luck! And May the Stars be With You!

Note: This Exam and answer key will be published on the Las Vegas Astronomical Society website at http://www.lvastronomy.com. Harold Nations, Phd., Professor of Astronomy at the College of Southern Nevada, assisted in preparation of this exam.

Astronomy Questions for Science Olympiad

http://www.tufts.edu/as/wright_center/products/sci_olympiad/

http://www.tufts.edu/as/wright_center/products/sci_olympiad/

1. The object on the front of this exam was first observed in 1054 CE by ancient Chinese and Arab observers. This phenomenon is the result of a _Supernova____. A ___Pulsar__ is found at the center of this object. This phenomenon is still visible in the night sky and is commonly known as the ____Crab Nebula____ (Common name or catalog designation is acceptable.)

2. Identify the following deep sky objects by their general type:

! ! !

a: ____Galaxy___________! ! b:_Open Star Cluster! c: Globular Cluster_

! ! !

d: _Dark Nebula_________! ! e: Planetary Nebula_! f: ___Bright Nebula__

3. A starʼs trigonometric _parallax_, used to determine its distance, comes from observations of its position in the sky from opposite sides of the Earthʼs orbit made ___six____ months apart.

4. From hottest to coolest, the seven stellar Spectral Classifications are _O, B, A, F, G, K, M_.

5. A main sequence star, which is apparently five magnitudes or 100 times brighter than a second star of the same exact type is __ten___ times closer than its fainter twin.


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6. _White Dwarfs/Dwarves_ are stars that haves masses like that of the Sun and radii like that of the Earth. Our Sun will probably end its life as one of these.

7. The stars in the photo below are in the constellation _Auriga__. The common name of the

constellationʼs α-star is __Cappella_____.

αε

8. Epsilon __Aurigae__ (in the above photo) is an _eclipsing binary_ system. It is a target of special interest to astronomers between 2009 and 2011, because this is the period of its next _eclipse_.

9. Messier 42, the Great Orion Nebula, for observers in the United States, is the most obvious region of recent _star birth or star formation_ in our galaxy.

10.Star formation may be triggered by pressure or shock waves from supernovae, which aid gravity through compression of interstellar clouds to greater densities.


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11.Globular star clusters are the oldest and richest clusters in the galaxy. They are over ten billion years old.

12.Label the 6 major layers of a star:

1. A - Corona

2. B - Radiative/Radiation Zone

3. C - Core

4. D - Convective/Convection Zone

5. E - Photosphere

6. F - Chromosphere

13.The proton-proton cycle of the thermonuclear process in solar and less massive stars produces one atom of helium from four atoms of hydrogen. Later in the life of these stars, Helium is involved in the production of carbon, the heaviest element that will be forged by our Sun, in a process known as the Helium flash.

14.Most stars fall on or near the Main Sequence of the H-R Diagram because this stage is the longest stage in the stellar evolutionary process of all stars.

15.Stars similar in mass to our Sun are type “G” stars and will have life spans of about ten billion years.

16. In the order of first to last, the evolutionary stages of a star like our Sun would be Main Sequence, Giant, Planetary Nebula, and finally White Dwarf.

17.Type I supernovae result from White Dwarf stars, which have accreted sufficient additional mass via mass transfer from a close binary companion, while Type II


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supernovae result from massive or giant or supermassive stars, which have converted their nuclear fuel to iron .

18.A neutron star that is detectable by its rapid rotation and strong magnetic field is called a Pulsar .

19.Supernova explosions involving massive stars of 25 or more solar masses are believed to produce Black Holes as stellar remnants.

20.The discovery of Cepheid variables in the spiral arms of the Andromeda “spiral nebula” by Hubble finally allowed its distance to be measured, and proved that Curtiss was correct in arguing that it was another galaxy like our own.

21.The center of our Galaxy is in the direction of the constellation Sagittarius .

22.The luminosity of RR Lyrae stars is about 100 times that of the Sun.

23.The luminosity of Cepheid variable stars is proportional to their pulsation periods; therefore, stars with longer the pulsation periods have higher/greater/brighter luminosities.

24.According to Pogsonʼs Ratio, a 1st magnitude star is about 2.512 times as bright as a 2nd magnitude star. If Star A has an apparent magnitude of 2.5 and its binary companion, Star B, has an apparent magnitude of 8.5, Star A is approximately c:250 brighter than its companion.

! ! ! a: 6 times! b: 25 times! c: 250 times! d: 1,000 times

Given that a 1st magnitude star is 2.523 times as bright as a 2nd magnitude star, you would have to know that relationship exists for each increase in magnitude. The difference in magnitude between the two stars is 6 magnitudes; therefore:

2.512(8.5-2.5) = 2.5126 = approximately 250 times brighter


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25. If H0 = 70km/s/Mpc: Then the recessional velocity of a galaxy at a distance of 200Mpc is b: 1,400 km/s .

! ! a: 1,400 Mpc!! b: 1,400 km/s! c: 2.86 Mpc! d: 2.86 km/s

Using the formula for Recessional Velocity (v= H0D): v=70km/s/Mpc x 200Mpc = 1,400km/s

26. In accordance with the inverse-square law, as the distance to a star increases by a factor of 10, its apparent magnitude increases by five units of magnitude; therefore, the greatest distance at which an RR Lyrae star having an absolute magnitude of 0 could be seen by a telescope capable of detecting objects as faint as 20th magnitude is b: 100 kiloparsecs .

! a: 100 parsecs! b: 100 kiloparsecs! c: 10 megaparsecs! d: 100 megaparsecs

Using the information provided, for every 5 units increased in magnitude for a given star, there must be a corresponding increase in distance by a factor of 10. If any star having an absolute magnitude of 0, which is measured at 10 parsecs, increases in magnitude (gets dimmer) to magnitude 20, then its distance must have increased by five factors of 10. So, 10 x 10 x 10 x 10 x 10 = 100,000 parsecs or 100kiloparsecs.

27. Identify the following galaxies by common name or Messier or NGC designation.

a: M33/NGC598/Pinwheel/Triangulum Galaxy b: M31/NGC224/Andromeda Galaxy c:M82/NGC3034/Cigar Galaxy

28. With regard to the Milky Way Galaxy, Population I stars are young stars found in the disk of the galaxy, while Population II stars are older stars found in the galaxyʼs halo .

29.Sagittarius A* is a bright and very compact astronomical radio source located at the center of the Milky Way Galaxy and is likely to be the location of a super massive black hole .


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30. Identify the following galaxies by Type.

a: Eliptical b: Irregular c: Spiral

31.SD1994D was a Type Ia Supernova located in the outskirts of galaxy NGC 4566 (see photo below) that resulted when a white dwarf star exceeded the Chandrasekhar limit of about 1.38 solar masses by accreting mass from a binary companion.

32. G1 is a globular cluster located in the Andromeda galaxy.

33.Large gravitationally bound star systems consisting of hundreds of billions of stars and enough gas and dust to make billions more are called normal galaxies, while starburst


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SD1994D

1

.

.

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Expansion of the Universe 133

The two drawings below represent the same group of galaxies at two different points in timeduring the history of the universe.

Early Universe Universe Some Time Later

B~

~A

<0A

1) Examine the distance between the galaxies labeled A-E in the Early Universe.Are allthe galaxies the same distance from each other?

2) Describe how the universe changed in going from the Early Universe to the UniverseSome Time Later.

3) Do the galaxies appear to get bigger?

4) Based on your answer to Question 3, do you think the stars within a galaxy move awayfrom one another due to the expansion of the universe? Explain your reasoning.

5) Compare the amount that the distance between the D and C galaxies changed incomparison to the amount that the distance between the D and E galaxies changed.Which galaxy, C or E, appears to have moved farther from D?

6) If you were in the 0 galaxy, how would the A, B, C, and E galaxies appear to moverelative to your location?

@ Pearson Education, Inc.,Publishing as Pearson Addison-Wesley.

LECTURE TUTORIALSFOR INTRODUCTORYASTRONOMYSECOND EDITION

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galaxies are galaxies in which a violent event, such as a near collision, has caused a sudden intense burst of star formation.

Questions 34 thru 40: The two diagrams below represent the same group of galaxies at two different points in time during the history of the Universe.

Early Universe! ! ! ! The Universe Some Time Later

34. Examine the distances between the galaxies labeled A-E in both the Early Universe and the Universe Some Time Later. Describe how the Universe changed as time passed from the Early Universe to the Universe Some Time Later.

All of the galaxies moved away from all of the other galaxies. The distances between all of the galaxies increased.

35.Do the galaxies appear to become larger? No Do the stars within the galaxy move away from one another due to the expansion of the Universe? No Explain your reasoning.

The stars within a galaxy do not participate in the overall expansion of the Universe, as the galaxies do.


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36.Note how much the distance between galaxies D and C changed in comparison with how much the distance between galaxies D and E change. Which galaxy, C or E, appears to have moved farther from galaxy D? E If you were located in galaxy D, describe how galaxies A, B, C, and E would appear to move relative to your location?

The distance between galaxies D and C increased less than the distance between galaxies D and E. Galaxy E appears to have moved farther away from galaxy D. All of the galaxies appear to have moved father away from galaxy D.

37.You are still located in galaxy D observing the movement of galaxies A, B, C, and E. How does the speed with which each galaxy moves compare with the other galaxies as time passes from the Early Universe to the Universe Some Time Later? Rank the galaxies from the fastest to the slowest.

The galaxiesʼ speed ranked from fastest to slowest is B, E, A, C.

38. Now imagine that you are located in galaxy E. Rank galaxies A, B, C, and D in terms of their relative speeds away from you, from the fastest to the slowest.

Galaxies D and A appear to be tied in speed and distance, with C and then B next in order of speed.

39.What is the relationship between an objectʼs distance from you in the Universe and its recessional velocity, the speed it would appear to being moving away from you? Is your observation true for all locations within the Universe?

The galaxies which were originally further away all seem to have traveled the farthest and therefore traveled faster than those that were closer at the beginning. Given that the diagrams represent the entire Universe, this observation holds true for all locations within the Universe.


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40.Consider the following discussion between two students regarding the possible location of the center of the Universe:

! Student 1: Since all the galaxies we observe are moving away from us, we must be at the center of the Universe.

! Student 2:!If you look at the diagram, itʼs pretty clear that all the galaxies are moving away from each other, so I think each galaxy must be at the center of the Universe.

! Do you agree or disagree with either or both of the students? Explain your reasoning.

Neither student is correct. Depending on which galaxy you were located in, each galaxy would seem to be the center of the Universe, as all galaxies appear to be moving away from every other galaxy.


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