Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
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Textbook Question
Chapter 21, Problem 2E
Why is star formation more likely to occur in cold molecular clouds than in regions where the temperature of the interstellar medium is several hundred thousand degrees?
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Chapter 21 Solutions
Astronomy
Ch. 21 - Give several reasons the Orion molecular cloud is...Ch. 21 - Why is star formation more likely to occur in cold...Ch. 21 - Why have we learned a lot about star formation...Ch. 21 - Describe what happens when a star forms. Begin...Ch. 21 - Describe how the T Tauri star stage in the life of...Ch. 21 - Look at the four stages shown in Figure 21.8. In...Ch. 21 - The evolutionary track for a star of 1 solar mass...Ch. 21 - Two protostars, one 10 times the mass of the Sun...Ch. 21 - Compare the scale (size) of a typical dusty disk...Ch. 21 - Why is it so hard to see planets around other...
Ch. 21 - Why did it take astronomers until 1995 to discover...Ch. 21 - Which types of planets are most easily detected by...Ch. 21 - List three ways in which the exoplanets we have...Ch. 21 - List any similarities between discovered...Ch. 21 - What revisions to the theory of planet formation...Ch. 21 - Why are young Jupiters easier to see with direct...Ch. 21 - A friend of yours who did not do well in her...Ch. 21 - Observations suggest that it takes more than 3...Ch. 21 - Suppose you wanted to observe a planet around...Ch. 21 - Why were giant planets close to their stars the...Ch. 21 - Exoplanets in eccentric orbits experience large...Ch. 21 - When astronomers found the first giant planets...Ch. 21 - An exoplanetary system has two known planets....Ch. 21 - Kepler’s third law says that the orbital period...Ch. 21 - Calculate the transit depth for an M dwarf star...Ch. 21 - If a transit depth of 0.00001 can be detected with...Ch. 21 - What fraction of gas giant planets seems to have...
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- If the Sun were a member of the cluster NGC 2264, would it be on the main sequence yet? Why or why not?arrow_forwardDescribe the characteristics of the various kinds of interstellar gas (HII regions, neutral hydrogen clouds, ultra-hot gas clouds, and molecular clouds).arrow_forwardStars that have masses approximately 0.8 times the mass of the Sun take about 18 billion years to turn into red giants. How does this compare to the current age of the universe? Would you expect to find a globular cluster with a main-sequence turnoff for stars of 0.8 solar mass or less? Why or why not?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_forwardIf all the stars in a cluster have nearly the same age, why are clusters useful in studying evolutionary effects (different stages in the lives of stars)?arrow_forwardIf most stars become white dwarfs at the ends of their lives and the formation of white dwarfs is accompanied by the production of a planetary nebula, why are there more white dwarfs than planetary nebulae in the Galaxy?arrow_forward
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