Astronomy 210 Quiz 7, spring semester 2016
Cuesta College, San Luis Obispo, CA
According to the monolithic collapse model, the oldest stars in the Milky Way are located:
(A) in the halo.
(B) in the nuclear bulge.
(C) within the spiral arms.
(D) inside the central supermassive black hole.
Correct answer (highlight to unhide): (A)
According to the monolithic collapse model, the Milky Way evolved from a spherical shape to its current disk shape, leaving behind the globular clusters out in its halo. Thus globular clusters should all have the identical (old) ages (as determined from the lack of metal absorption lines, and their H-R diagram turn-off points), while the nuclear bulge and the spiral arms should be comprised of mixed-age (old and newer) stars.
Section 30674
Exam code: quiz07N4rK
(A) : 10 students
(B) : 1 student
(C) : 6 students
(D) : 0 students
"Success level": 61% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.47
Showing posts with label monolithic collapse. Show all posts
Showing posts with label monolithic collapse. Show all posts
20160504
Astronomy in-class activity: monolithic collapse hypothesis, stellar populations
Astronomy 210 In-class activity 22 v.16.05.04, spring semester 2016
Cuesta College, San Luis Obispo, CA
Students find their assigned groups of three to four students, and work cooperatively on an in-class activity worksheet to discuss different metallicities and ages of stars in the monolithic collapse hypothesis of the Milky Way.
Cuesta College, San Luis Obispo, CA
Students find their assigned groups of three to four students, and work cooperatively on an in-class activity worksheet to discuss different metallicities and ages of stars in the monolithic collapse hypothesis of the Milky Way.
20130428
Astronomy quiz question: Milky Way capture of dwarf galaxies
Astronomy 210 Quiz 6, spring semester 2013
Cuesta College, San Luis Obispo, CA
__________ is evidence that small galaxies were captured by the growing Milky Way.
(A) Halo dark matter.
(B) The sun's absorption lines.
(C) Different ages of globular clusters.
(D) Stars orbiting the central supermassive black hole.
Correct answer: (C)
According to the monolithic collapse model, the Milky Way evolved from a spherical shape to its current disk shape, leaving behind the globular clusters out in its halo. Thus globular clusters should all have the identical (old) ages (as determined from the lack of metal absorption lines, and their H-R diagram turn-off points), while the disk should be comprised of mixed age (old and newer) stars. However, the presence of globular clusters of different ages indicates that they may have been inherited from smaller dwarf galaxies.
Section 30674
Exam code: quiz06Nu1N
(A) : 0 students
(B) : 1 student
(C) : 26 students
(D) : 1 student
Success level: 94% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0
Section 30676
Exam code: quiz06Sl6n
(A) : 7 students
(B) : 2 students
(C) : 24 students
(D) : 8 students
Success level: 65% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.41
Cuesta College, San Luis Obispo, CA
__________ is evidence that small galaxies were captured by the growing Milky Way.
(A) Halo dark matter.
(B) The sun's absorption lines.
(C) Different ages of globular clusters.
(D) Stars orbiting the central supermassive black hole.
Correct answer: (C)
According to the monolithic collapse model, the Milky Way evolved from a spherical shape to its current disk shape, leaving behind the globular clusters out in its halo. Thus globular clusters should all have the identical (old) ages (as determined from the lack of metal absorption lines, and their H-R diagram turn-off points), while the disk should be comprised of mixed age (old and newer) stars. However, the presence of globular clusters of different ages indicates that they may have been inherited from smaller dwarf galaxies.
Section 30674
Exam code: quiz06Nu1N
(A) : 0 students
(B) : 1 student
(C) : 26 students
(D) : 1 student
Success level: 94% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0
Section 30676
Exam code: quiz06Sl6n
(A) : 7 students
(B) : 2 students
(C) : 24 students
(D) : 8 students
Success level: 65% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.41
20121123
Astronomy quiz question: Milky Way capture of dwarf galaxies
Astronomy 210 Quiz 6, fall semester 2012
Cuesta College, San Luis Obispo, CA
Evidence that small galaxies were captured by the growing Milky Way is/are:
(A) different ages of globular clusters.
(B) metal-rich absorption lines in the sun.
(C) dark matter in the halo.
(D) stars orbiting the central supermassive black hole.
Correct answer: (A)
According to the monolithic collapse model, the Milky Way evolved from a spherical shape to its current disk shape, leaving behind the globular clusters out in its halo. Thus globular clusters should all have the identical (old) ages (as determined from the lack of metal absorption lines, and their H-R diagram turn-off points), while the disk should be comprised of mixed age (old and newer) stars. However, the presence of globular clusters of different ages indicates that they may have been inherited from smaller dwarf galaxies.
Section 70160
Exam code: quiz06n4Rd
(A) : 18 students
(B) : 4 students
(C) : 0 students
(D) : 3 students
Success level: 75% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.57
Cuesta College, San Luis Obispo, CA
Evidence that small galaxies were captured by the growing Milky Way is/are:
(A) different ages of globular clusters.
(B) metal-rich absorption lines in the sun.
(C) dark matter in the halo.
(D) stars orbiting the central supermassive black hole.
Correct answer: (A)
According to the monolithic collapse model, the Milky Way evolved from a spherical shape to its current disk shape, leaving behind the globular clusters out in its halo. Thus globular clusters should all have the identical (old) ages (as determined from the lack of metal absorption lines, and their H-R diagram turn-off points), while the disk should be comprised of mixed age (old and newer) stars. However, the presence of globular clusters of different ages indicates that they may have been inherited from smaller dwarf galaxies.
Section 70160
Exam code: quiz06n4Rd
(A) : 18 students
(B) : 4 students
(C) : 0 students
(D) : 3 students
Success level: 75% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.57
20111117
Astronomy quiz question: monolithic collapse model
Astronomy 210 Quiz 6, fall semester 2011
Cuesta College, San Luis Obispo, CA
According to the monolithic collapse model, there should be no young stars in globular clusters because:
(A) metal-rich stars in the halo have already become metal-poor stars.
(B) there are no metals left in the halo.
(C) dark matter in the halo prevents new stars from forming.
(D) interstellar hydrogen in the halo moved into the disk.
Correct answer: (D).
Since the distribution of interstellar hydrogen in the Milky Way has flattened from spherical to disk-shaped, new star formation occurs only in the disk, and not in the halo, where the first generation stars of the globular clusters are located.
Section 70160
Exam code: quiz06n4Nd
(A) : 11 students
(B) : 4 students
(C) : 2 students
(D) : 9 students
Success level: 40% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.63
Cuesta College, San Luis Obispo, CA
According to the monolithic collapse model, there should be no young stars in globular clusters because:
(A) metal-rich stars in the halo have already become metal-poor stars.
(B) there are no metals left in the halo.
(C) dark matter in the halo prevents new stars from forming.
(D) interstellar hydrogen in the halo moved into the disk.
Correct answer: (D).
Since the distribution of interstellar hydrogen in the Milky Way has flattened from spherical to disk-shaped, new star formation occurs only in the disk, and not in the halo, where the first generation stars of the globular clusters are located.
Section 70160
Exam code: quiz06n4Nd
(A) : 11 students
(B) : 4 students
(C) : 2 students
(D) : 9 students
Success level: 40% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.63
20110425
Astronomy quiz question: Milky Way monolithic collapse evidence
Astronomy 210 Quiz 6, Spring Semester 2011
Cuesta College, San Luis Obispo, CA
Evidence that the Milky Way became thinner and flatter as it evolved is:
(A) that halo population stars have fewer absorption lines than disk population stars.
(B) the presence of spiral arms that stretch out from the nuclear bulge to the edges.
(C) that halo population stars are less luminous than disk population stars.
(D) that dark matter is located out in the halo, but not in the disk.
Correct answer: (A)
In the monolithic collapse model for the evolution of the Milky Way, its shape evolved from spherical to thinner and flatter over time, as supported by the older generation metal-poor stars found in the halo, versus the younger metal-rich stars found in the disk (which would have more metal absorption lines in their spectra).
Section 30676
Exam code: quiz06SoR3
(A) : 12 students
(B) : 15 students
(C) : 9 students
(D) : 3 students
"Success level": 36% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.55
Cuesta College, San Luis Obispo, CA
Evidence that the Milky Way became thinner and flatter as it evolved is:
(A) that halo population stars have fewer absorption lines than disk population stars.
(B) the presence of spiral arms that stretch out from the nuclear bulge to the edges.
(C) that halo population stars are less luminous than disk population stars.
(D) that dark matter is located out in the halo, but not in the disk.
Correct answer: (A)
In the monolithic collapse model for the evolution of the Milky Way, its shape evolved from spherical to thinner and flatter over time, as supported by the older generation metal-poor stars found in the halo, versus the younger metal-rich stars found in the disk (which would have more metal absorption lines in their spectra).
Section 30676
Exam code: quiz06SoR3
(A) : 12 students
(B) : 15 students
(C) : 9 students
(D) : 3 students
"Success level": 36% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.55
20101129
Astronomy midterm question: monolithic collapse model
Astronomy 210 Midterm 2, Fall Semester 2010
Cuesta College, San Luis Obispo, CA
[20 points.] Discuss the evidence for the monolithic collapse model of the Milky Way (spherical gas cloud flattening into a disk). Support your answer using the orbit and metal content properties of halo stars versus disk stars.
Solution and grading rubric:
Section 70160
p: 17 students
r: 8 students
t: 4 students
v: 6 students
x: 3 students
y: 3 students
z: 0 students
A sample "p" response (from student 1991):
Cuesta College, San Luis Obispo, CA
[20 points.] Discuss the evidence for the monolithic collapse model of the Milky Way (spherical gas cloud flattening into a disk). Support your answer using the orbit and metal content properties of halo stars versus disk stars.
Solution and grading rubric:
- p = 20/20:
Correct. Discusses evidence supporting the flattening of the Milky Way's shape by explaining how metal content increases for younger generations of stars, and observations that disk stars are metal-rich compared to the metal-poor halo stars above and below the disk. - r = 16/20:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. - t = 12/20:
Contains right ideas, but discussion is unclear/incomplete or contains major errors. - v = 8/20:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. At least some discussion related to the monolothic collapse model. - x = 4/20:
Implementation/application of ideas, but credit given for effort rather than merit. Discussion unrelated to the monolithic collapse model.
y = 2/20: Irrelevant discussion/effectively blank. - y = 2/20:
Irrelevant discussion/effectively blank. - z = 0/20:
Blank.
Section 70160
p: 17 students
r: 8 students
t: 4 students
v: 6 students
x: 3 students
y: 3 students
z: 0 students
A sample "p" response (from student 1991):
20100430
Astronomy quiz question: contradicting the monolithic collapse model
Astronomy 210 Quiz 6, Spring Semester 2010
Cuesta College, San Luis Obispo, CA
The monolithic collapse model is contradicted by which recent observation(s)?
(A) The sun has metal absorption lines.
(B) Not all globular clusters have the same age.
(C) Globular clusters with randomly tipped, elliptical orbits.
(D) The presence of dark matter in the halo.
Correct answer: (B)
According to the monolithic collapse model, material in the Milky Way had a spherical distribution, and the first generation of stars were born in globular clusters. These globular clusters were left behind in the halo of the Milky Way as matter collapsed into a thin disk. With no new material left in the halo, the only new star formation is in the disk of the Milky Way, which have higher metallicity, being made from the remnants of earlier massive stars.
Response (B) contradicts the monolithic collapse model, as it is expected that all globular cluster stars would only have formed before the collapse of material in the current disk of the Milky Way.
Response (A) is consistent with the monolithic collapse model, as is (C). Response (D) is a true statement that does not explicitly contradict the monolithic collapse model.
Section 30676
(A) : 4 students
(B) : 37 students
(C) : 18 students
(D) : 11 students
"Success level": 57% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.62
Cuesta College, San Luis Obispo, CA
The monolithic collapse model is contradicted by which recent observation(s)?
(A) The sun has metal absorption lines.
(B) Not all globular clusters have the same age.
(C) Globular clusters with randomly tipped, elliptical orbits.
(D) The presence of dark matter in the halo.
Correct answer: (B)
According to the monolithic collapse model, material in the Milky Way had a spherical distribution, and the first generation of stars were born in globular clusters. These globular clusters were left behind in the halo of the Milky Way as matter collapsed into a thin disk. With no new material left in the halo, the only new star formation is in the disk of the Milky Way, which have higher metallicity, being made from the remnants of earlier massive stars.
Response (B) contradicts the monolithic collapse model, as it is expected that all globular cluster stars would only have formed before the collapse of material in the current disk of the Milky Way.
Response (A) is consistent with the monolithic collapse model, as is (C). Response (D) is a true statement that does not explicitly contradict the monolithic collapse model.
Section 30676
(A) : 4 students
(B) : 37 students
(C) : 18 students
(D) : 11 students
"Success level": 57% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.62
20091223
Astronomy final exam question: halo stars likely for life?
Astronomy 210 Final Exam, fall semester 2009
Cuesta College, San Luis Obispo, CA
Halo stars of the Milky Way would not be likely places to find life because halo stars:
(A) are metal-poor.
(B) are not massive enough.
(C) are not old enough.
(D) have too much dark matter.
Correct answer (highlight to unhide): (A)
Halo stars are the first generation of stars born in the Milky Way, and thus would be metal-poor, as well as their planets, which would then not have "metals" (any elements heavier than hydrogen, which would include carbon and oxygen).
Section 70160
(A) : 27 students
(B) : 4 students
(C) : 4 students
(D) : 6 students
Success level: 69% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.11
Cuesta College, San Luis Obispo, CA
Halo stars of the Milky Way would not be likely places to find life because halo stars:
(A) are metal-poor.
(B) are not massive enough.
(C) are not old enough.
(D) have too much dark matter.
Correct answer (highlight to unhide): (A)
Halo stars are the first generation of stars born in the Milky Way, and thus would be metal-poor, as well as their planets, which would then not have "metals" (any elements heavier than hydrogen, which would include carbon and oxygen).
Section 70160
(A) : 27 students
(B) : 4 students
(C) : 4 students
(D) : 6 students
Success level: 69% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.11
20091130
Astronomy midterm question: globular cluster metallicity
Astronomy 210 Midterm 2, Fall Semester 2009
Cuesta College, San Luis Obispo, CA
[20 points.] Discuss whether globular cluster stars in the halo of the Milky Way are expected to be metal-rich or metal-poor, and why. Explain using the properties of mass and stellar lifetimes, and the Milky Way.
Solution and grading rubric:
Section 70158
p: 14 students
r: 6 students
t: 9 students
v: 22 students
x: 0 students
y: 0 students
z: 0 students
A sample "p" response (from student 9221), with a fanciful depiction of increasing metallicity in subsequent generations of stars:
A more conventional sample "p" response (from student 1520):
Another sample "p" response (from student 1204), illustrating the monolithic collapse model:
A sample "v" response (from student 6636), typically discussing how stars use up metals over time to eventually become old and metal-poor:
Cuesta College, San Luis Obispo, CA
[20 points.] Discuss whether globular cluster stars in the halo of the Milky Way are expected to be metal-rich or metal-poor, and why. Explain using the properties of mass and stellar lifetimes, and the Milky Way.
Solution and grading rubric:
- p = 20/20:
Correct. Globular cluster stars in the halo are the old first-generation stars that formed when the Milky Way was spherical in shape and are composed primarily of hydrogen with little metal content, as metal content increases over time due to stars fusing and releasing fusion products to subsequent generations. - r = 16/20:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. Complete explanation of why metal-poor stars are older than metal-rich stars, but discussion of why the halo is the oldest part of the Milky Way is problematic, or vice versa. - t = 12/20:
Contains right ideas, but discussion is unclear/incomplete or contains major errors. As (r), but discussion of why the halo is the oldest part of the Milky Way is missing, or vice versa. - v = 8/20:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Has only problematic discussion of how metal-poor stars are old stars (e.g., metals are used up by stars over time). - x = 4/20:
Implementation/application of ideas, but credit given for effort rather than merit. Implausible evidence/methods/discussion. - y = 2/20:
Irrelevant discussion/effectively blank. - z = 0/20:
Blank.
Section 70158
p: 14 students
r: 6 students
t: 9 students
v: 22 students
x: 0 students
y: 0 students
z: 0 students
A sample "p" response (from student 9221), with a fanciful depiction of increasing metallicity in subsequent generations of stars:
A more conventional sample "p" response (from student 1520):
Another sample "p" response (from student 1204), illustrating the monolithic collapse model:
A sample "v" response (from student 6636), typically discussing how stars use up metals over time to eventually become old and metal-poor:
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