Horizons: Exploring the Universe (MindTap Course List)
14th Edition
ISBN: 9781305960961
Author: Michael A. Seeds, Dana Backman
Publisher: Cengage Learning
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Question
Chapter 12, Problem 8RQ
To determine
For what reason does self-sustaining star formation produce clouds of stars that resemble segments of spiral arms?
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What evidence is there that star formation has occurred recently?
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QUESTION 16
Use the figure shown below to complete the following statement: A low-mass protostar (0.5 to 8M the mass compared to our sun) remains roughly constant in
decreases in
until it makes a turn towards the main sequence, as it follows its evolutionary track.
Protostars of different masses follow diferent
paths on their way to the main sequence.
107
Luminosity (L)
10
105
10
107
10²
101
1
10-1
10-2
10-3
Spectral
type
0.01 R
0.001
Re
60 M
MAIN SEQUENCE
40,000 30,000
20 Mau
10 Mgun
5 Mun
0.1 Run
Ren
radius; temperature
luminosity; radius
3 Min.
05 BO
temperature; luminosity
Oluminosity: temperature
radius: luminosity
1 M
10,000 6000
Surlace temperature (K)
1,000 Rs
2 M STAR
L
0.8 M
B5 AO FOGO КБ МБ
-10
+10
3000
Absolute visual magnitude
and
Chapter 12 Solutions
Horizons: Exploring the Universe (MindTap Course List)
Ch. 12 - Why is it difficult to specify the dimensions of...Ch. 12 - Why didn’t astronomers before Shapley realize how...Ch. 12 - Prob. 3RQCh. 12 - Prob. 4RQCh. 12 - Prob. 5RQCh. 12 - Prob. 6RQCh. 12 - Prob. 7RQCh. 12 - Prob. 8RQCh. 12 - Prob. 9RQCh. 12 - Prob. 10RQ
Ch. 12 - Prob. 11RQCh. 12 - Prob. 12RQCh. 12 - Prob. 13RQCh. 12 - Prob. 14RQCh. 12 - Prob. 15RQCh. 12 - Prob. 16RQCh. 12 - Prob. 1DQCh. 12 - Prob. 2DQCh. 12 - Prob. 1PCh. 12 - Prob. 2PCh. 12 - Prob. 3PCh. 12 - Prob. 4PCh. 12 - Prob. 5PCh. 12 - Prob. 6PCh. 12 - Prob. 7PCh. 12 - If the Sun is 4.6 billion years old, how many...Ch. 12 - Prob. 9PCh. 12 - Prob. 10PCh. 12 - Prob. 11PCh. 12 - Prob. 12PCh. 12 - Prob. 1LTLCh. 12 - Prob. 2LTL
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- Are supergiant stars also extremely massive? Explain the reasoning behind your answer.arrow_forwardArrange the following stars in order of their evolution: A. A star with no nuclear reactions going on in the core, which is made primarily of carbon and oxygen. B. A star of uniform composition from center to surface; it contains hydrogen but has no nuclear reactions going on in the core. C. A star that is fusing hydrogen to form helium in its core. D. A star that is fusing helium to carbon in the core and hydrogen to helium in a shell around the core. E. A star that has no nuclear reactions going on in the core but is fusing hydrogen to form helium in a shell around the core.arrow_forwardLook at the four stages shown in Figure 21.8. In which stage(s) can we see the star in visible light? In infrared radiation? Figure 21.8 Formation of a Star. (a) Dense cores form within a molecular cloud. (b) A protostar with a surrounding disk of material forms at the center of a dense core, accumulating additional material from the molecular cloud through gravitational attraction. (c) A stellar wind breaks out but is confined by the disk to flow out along the two poles of the star. (d) Eventually, this wind sweeps away the cloud material and halts the accumulation of additional material, and a newly formed star, surrounded by a disk, becomes observable. These sketches are not drawn to the same scale. The diameter of a typical envelope that is supplying gas to the newly forming star is about 5000 AU. The typical diameter of the disk is about 100 AU or slightly larger than the diameter of the orbit of Pluto.arrow_forward
- According to the text, a star must be hotter than about 25,000 K to produce an H II region. Both the hottest white dwarfs and main-sequence O stars have temperatures hotter than 25,000 K. Which type of star can ionize more hydrogen? Why?arrow_forwardIn the HR diagrams for some young clusters, stars of both very low and very high luminosity are off to the right of the main sequence, whereas those of intermediate luminosity are on the main sequence. Can you offer an explanation for that? Sketch an HR diagram for such a cluster.arrow_forwardYou have discovered two star clusters. The first cluster contains mainly main-sequence stars, along with some red giant stars and a few white dwarfs. The second cluster also contains mainly main-sequence stars, along with some red giant stars, and a few neutron stars-but no white dwarf stars. What are the relative ages of the clusters? How did you determine your answer?arrow_forward
- You 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_forwardWhich statement is most logical? a First stars are thought to have been more massive than Sun because the materials used to make clouds were more abundant at the beginning b First stars are thought to have been more massive than Sun because the temperatures of the clouds that made them were higher because they consisted entirely of hydrogen and helium c First stars are thought to have been more massive than Sun because star-forming clouds were much denser early in time d First stars are thought to have been more massive than Sun because the clouds that made them were much more massivearrow_forwardFor a main sequence star with luminosity L, how many kilograms of hydrogen is being converted into helium per second? Use the formula that you derive to estimate the mass of hydrogen atoms that are converted into helium in the interior of the sun (LSun = 3.9 x 1026 W). (Note: the mass of a hydrogen atom is 1 mproton and the mass of a helium atom is 3.97 mproton. You need four hydrogen nuclei to form one helium nucleus.)arrow_forward
- As a cluster of stars begins to age, which type of star in the cluster will move off the main sequence of the H-R diagram first? 1) all the stars in a cluster are born at the same time; so they will all move off the main sequence at the same time, as they evolve 2) G type stars, like our Sun 3) M type stars, which are the coolest 4) the lowest mass stars, which have the least amount of fuel for fusion 5) the O and B type starsarrow_forwardLooking for ___ pcarrow_forwardThe Orion Nebula is about 20 light-years (20 × 1018 cm) across, enclosing a roughly spherical area with a volume of 4.19 × 1057 cm3. Calculate the number of 0.1 solar mass stars that might be formed in such a nebula. Assume that the nebula has a density of 1000 atoms/cm3.arrow_forward
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