21st Century Astronomy
6th Edition
ISBN: 9780393428063
Author: Kay
Publisher: NORTON
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Chapter 20, Problem 8QP
To determine
A globular cluster with no variable stars would have been left out of Shapley’s study.
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Students have asked these similar questions
If the stars at the turnoff point of a cluster have a mass of 3 M, what is the age of the cluster?
a.
3.0 × 1010 years
b.
3.3 × 109 years
c.
6.4 × 108 years
d.
1.6 × 1011 years
e.
The age of a star cluster cannot be determined from the mass of stars at the turnoff point.
Star clusters are important to our study of stars because
a.
all stars formed in star clusters.
b.
the sun was once a member of a globular cluster.
c.
they give us a method to test our theories and models of stellar evolution.
d.
they are the only objects that contain Cepheid variables.
e.
all of the above are true.
3. Brown dwarfs are ____. a. stars with a very thick dust sphere around them, so they appear “brown” b. low mass M type stars with hundreds of planets c. an anomaly because they are extremely small but have relatively high temperature d. protostars that could not ignite the fusion of hydrogen at their core e. has a surface temperature of 2500 K by fusing hydrogen
I asked this question onece already, but the answer I got said the answer was C because "AT 2700K THEY ARE HOT" or something to that effect. I tried to find a way to reply to that thread. My argument was that even if brown dwarfs were 2700k (and my book says that's closer to the temperature of red dwarfs and that brown dwarfs are usually around 1000K). Seeing that we are studying the life cycle and evolution of all stars, wouldn't either of those temperatures be on the relatively COOL side of all star temperatures? Wouldn't the most appropriate answer be D.?
Chapter 20 Solutions
21st Century Astronomy
Ch. 20.1 - Prob. 20.1CYUCh. 20.2 - Prob. 20.2CYUCh. 20.3 - Prob. 20.3CYUCh. 20.4 - Prob. 20.4CYUCh. 20 - Prob. 1QPCh. 20 - Prob. 2QPCh. 20 - Prob. 3QPCh. 20 - Prob. 4QPCh. 20 - Prob. 5QPCh. 20 - Prob. 6QP
Ch. 20 - Prob. 7QPCh. 20 - Prob. 8QPCh. 20 - Prob. 9QPCh. 20 - Prob. 10QPCh. 20 - Prob. 11QPCh. 20 - Prob. 12QPCh. 20 - Prob. 13QPCh. 20 - Prob. 14QPCh. 20 - Prob. 15QPCh. 20 - Prob. 16QPCh. 20 - Prob. 17QPCh. 20 - Prob. 18QPCh. 20 - Prob. 19QPCh. 20 - Prob. 20QPCh. 20 - Prob. 21QPCh. 20 - Prob. 22QPCh. 20 - Prob. 23QPCh. 20 - Prob. 24QPCh. 20 - Prob. 25QPCh. 20 - Prob. 26QPCh. 20 - Prob. 27QPCh. 20 - Prob. 28QPCh. 20 - Prob. 29QPCh. 20 - Prob. 30QPCh. 20 - Prob. 31QPCh. 20 - Prob. 32QPCh. 20 - Prob. 33QPCh. 20 - Prob. 34QPCh. 20 - Prob. 35QPCh. 20 - Prob. 36QPCh. 20 - Prob. 37QPCh. 20 - Prob. 38QPCh. 20 - Prob. 39QPCh. 20 - Prob. 40QPCh. 20 - Prob. 41QPCh. 20 - Prob. 42QPCh. 20 - Prob. 43QPCh. 20 - Prob. 44QPCh. 20 - Prob. 45QP
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- The chemical abundance of population I stars a. indicates that they were formed before the population II stars. b. indicates that the material they formed from had been enriched with material from supernovae. c. indicates that they contain very few heavy metals compared to halo stars. d. depends on the temperature of the star. e. depends on the mass of the star.arrow_forwardThe Hertzsprung-Russell diagram contains a region called the main sequence. Stars on this sequence have specific characteristics not found in other stars. What are these characteristics? a.Stars on the Hertzsprung-Russell diagram main sequence have roughly the same age. b.Stars on the main sequence of the Hertzsprung-Russell diagram are all roughly the same radius. c.Stars on the main sequence of the Hertzsprung-Russell diagram have an orderly arrangement of stellar masses, decreasing in mass from lower right to upper left. d.Stars on the main sequence of a Hertzsprung-Russell diagram do not produce heavy elements like iron. e.Stars on the main sequence of a Hertzsprung-Russell diagram all generate energy from nuclear fusion. f.None of the mentioned choices. Aristotle was a great Greek philosopher with many amazing ideas. Which of these statements about him is not true? a.Many of his claims about physics and astronomy were wrong. b.He was the first person to recognize…arrow_forward4. Suppose we observe a binary star system in which one star is much more massive than the other and both are on the main sequence. We measure that the smaller star orbits the larger at a distance of 10¹3 m with a speed of 10 m/s. a. What is the mass of the larger star? b. Which star has a higher luminosity? c. Which has a larger radius? d. Which is hotter?arrow_forward
- A group of 10 to 100 stars that formed at the same time but are so widely scattered in space their mutual gravity cannot hold them together is called a. a globular cluster. b. an open cluster. c. an association. d. a spherical component e. an accretion disk.arrow_forwardWhich of the following binary star systems cannot exist? A. A 1 solar-mass main sequence star and a 4 solar mass red giant with a size 100 times smaller than the orbital distance. B. A 15 solar-mass main sequence star and a 10 solar mass red giant with a size 100 times smaller than the orbital distance. C. A 1 solar-mass main sequence star and a 4 solar-mass main sequence star. D. A 2 solar-mass main sequence star and a 1 solar mass red giant with a size a few times smaller than the orbital distance.arrow_forwardAll massive main sequence stars reside in clouds of glowing gas. The four powerful stars in the center of the Orion Nebula are good examples. Lower mass stars like the Sun generally don't have clouds of gas around them. a. Why do powerful stars reside in gas clouds? b. What is making the gas glow exactly? For the last question, refer to the surface temperature of these stars, and to Wien's Law.arrow_forward
- Based on what you know about main-sequence stars, select all of the correct statements from the following list. 1. Since the interiors of stars cannot be observed, there are no theories about their structure. 2. More massive stars are hotter and brighter. 3. The weight of a star must be balanced by internal pressure. 4. More massive stars live longer; they take longer to use up all their energy. 5. Stars change position on the main sequence throughout their lives. 6. Outward energy flow in a star is by conduction only.arrow_forwardWhich of the following statements is wrong? A. A main-sequence star is cooler and brighter than it was as a protostar. B. Carbon fusion occurs in high-mass stars but not in low-mass stars because the cores of low-mass stars never contain significant amounts of carbon. C. when a main-sequence star exhausts its core hydrogen fuel supply, the core shrinks while the rest of the star expands. D. After a supernova explosion, the remains of the stellar core will be either a neutron star or a black hole.arrow_forwardAbsorption lines produced when starlight travels through the interstellar medium indicate that some components of the interstellar medium are cold and of a very low density because a. the lines are blueshifted. b. the lines are redshifted. c. the lines are extremely broad. d. the lines are extremely narrow. e. the lines are much darker than the stellar lines.arrow_forward
- The oldest globular clusters are a. 3 to 4 billion years old. b. 6 to 7 billion years old. c. 9 to 10 billion years old. d. 12 to 13 billion years old. e. 16 to 17 billion years old.arrow_forwardYou can use the equation in Exercise 22.34 to estimate the approximate ages of the clusters in Figure 22.10, Figure 22.12, and Figure 22.13. Use the information in the figures to determine the luminosity of the most massive star still on the main sequence. Now use the data in Table 18.3 to estimate the mass of this star. Then calculate the age of the cluster. This method is similar to the procedure used by astronomers to obtain the ages of clusters, except that they use actual data and model calculations rather than simply making estimates from a drawing. How do your ages compare with the ages in the text? Figure 22.10 NGC 2264 HR Diagram. Compare this HR diagram to that in Figure 22.8; although the points scatter a bit more here, the theoretical and observational diagrams are remarkably, and satisfyingly, similar. Figure 22.12 Cluster M41. (a) Cluster M41 is older than NGC 2264 (see Figure 22.10) and contains several red giants. Some of its more massive stars are no longer close to the zero-age main sequence (red line). (b) This ground-based photograph shows the open cluster M41. Note that it contains several orange-color stars. These are stars that have exhausted hydrogen in their centers, and have swelled up to become red giants. (credit b: modification of work by NOAO/AURA/NSF) Figure 22.13 HR Diagram for an Older Cluster. We see the HR diagram for a hypothetical older cluster at an age of 4.24 billion years. Note that most of the stars on the upper part of the main sequence have turned off toward the red-giant region. And the most massive stars in the cluster have already died and are no longer on the diagram. Characteristics of Main-Sequence Starsarrow_forwardExplain how an HR diagram of the stars in a cluster can be used to determine the age of the cluster.arrow_forward
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