Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 22, Problem 35E
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 H−R Diagram. Compare this H−R 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 H−R Diagram for an Older Cluster. We see the H−R 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 Stars
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
Finally estimate the lifetime of an M0 spectral type star if the total mass of the star is M = 0.51M⊙ , and it has a total luminosity L = 7.7× 10−2L⊙. Make the same assumptions as the previous two problems. How does your calculated Main Sequence lifetime for the M0 type star compare to the Main Sequence lifetime you calculated for the Sun?
The mass-luminosity relation describes the mathematical relationship between luminosity and mass for main sequence stars. It describes how a star with a mass of 4 M⊙ would have a luminosity of ______ L⊙.
If a star has a radius 1/2 that of the Sun and a temperature 4 that of the Sun, how many times higher is the star's luminosity than that of the Sun? (If it is smaller by a factor of 8, you would write 0.125 because 1/8=0.125)
If a star has a radius 2 times larger than the Sun's and a luminosity 1/4th that of the Sun, how many times higher is the star's temperature than that of the Sun? (If it is smaller by a factor of 8, you would write 0.125 because 1/8=0.125)
If a star has a surface temperature 2 times lower than the Sun's and a luminosity the same as the Sun, how many times larger is the star than the Sun? (If it is smaller by a factor of 8, you would write 0.125 because 1/8=0.125)
A star with spectral type A0 has a surface temperature of 9600 K and a radius of 2.2 RSun. How many times more luminous is this star than the Sun? (if it is less luminous enter a number less than one)
This star has a mass of 3.3 MSun. Using the simple approximation that we made in class, what is the main sequence lifetime of this star? You may assume that the lifetime of the sun is 1010 yr.
Compare this to the lifetime of a A0 star listed in Table 22.1 (computed using a more sophisticated approach). Is the value you calculated in the previous problem longer or shorter than what is reported in the table? (L for longer, S for shorter) (You only get one try at this problem.)
Chapter 22 Solutions
Astronomy
Ch. 22 - Compare the following stages in the lives of a...Ch. 22 - What is the first event that happens to a star...Ch. 22 - Astronomers find that 90% of the stars observed in...Ch. 22 - Describe the evolution of a star with a mass...Ch. 22 - Describe the evolution of a star with a mass...Ch. 22 - A star is often described as “moving” on an HR...Ch. 22 - On which edge of the main sequence band on an HR...Ch. 22 - How do stars typically “move” through the main...Ch. 22 - Certain stars, like Betelgeuse, have a lower...Ch. 22 - Gravity always tries to collapse the mass of a...
Ch. 22 - Why are star clusters so useful for astronomers...Ch. 22 - Would the Sun more likely have been a member of a...Ch. 22 - Suppose you were handed two HR diagrams for two...Ch. 22 - Referring to the HR diagrams in Exercise 22.13,...Ch. 22 - The nuclear process for fusing helium into carbon...Ch. 22 - Pictures of various planetary nebulae show a...Ch. 22 - Describe the two “recycling” mechanisms that are...Ch. 22 - In which of these star groups would you mostly...Ch. 22 - Explain how an HR diagram of the stars in a...Ch. 22 - Where did the carbon atoms in the trunk of a tree...Ch. 22 - What is a planetary nebula? Will we have one...Ch. 22 - Is the Sun on the zero-age main sequence? Explain...Ch. 22 - How are planetary nebulae comparable to a...Ch. 22 - Which of the planets in our solar system have...Ch. 22 - Would you expect to find an earthlike planet (with...Ch. 22 - In the HR diagrams for some young clusters, stars...Ch. 22 - If the Sun were a member of the cluster NGC 2264,...Ch. 22 - If all the stars in a cluster have nearly the same...Ch. 22 - Suppose a star cluster were at such a large...Ch. 22 - Suppose an astronomer known for joking around told...Ch. 22 - Stars that have masses approximately 0.8 times the...Ch. 22 - Automobiles are often used as an analogy to help...Ch. 22 - The text says a star does not change its mass very...Ch. 22 - The text explains that massive stars have shorter...Ch. 22 - You can use the equation in Exercise 22.34 to...Ch. 22 - You can estimate the age of the planetary nebula...Ch. 22 - If star A has a core temperature T, and star B has...
Additional Science Textbook Solutions
Find more solutions based on key concepts
If youre in a spaceship moving at 0.95c relative to Earth, do you perceive time to be passing more slowly than ...
Essential University Physics: Volume 2 (3rd Edition)
What changes during a chemical reaction?
Conceptual Integrated Science
There are no lakes or seas on Mars today.
Life in the Universe (4th Edition)
Much of The 935 near the Sun is atomic hydrogen. Its temperature would have to be 1.5107K for the average veloc...
College Physics
Express the unit vectors in terms of (that is, derive Eq. 1.64). Check your answers several ways Also work o...
Introduction to Electrodynamics
Explain all answers clearly, with complete sentences and proper essay structure if needed. An asterisk (*) desi...
The Cosmic Perspective Fundamentals (2nd Edition)
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- Explain how an HR diagram of the stars in a cluster can be used to determine the age of the cluster.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_forwardDescribe the evolution of a star with a mass similar to that of the Sun, from the protostar stage to the time it first becomes a red giant. Give the description in words and then sketch the evolution on an HR diagram.arrow_forward
- If a 100 solar mass star were to have a luminosity of 107 times the Sun’s luminosity, how would such a star’s density compare when it is on the main sequence as an O-type star, and when it is a cool supergiant (M-type)? Use values of temperature from Figure 18.14 or Figure 18.15 and the relationship between luminosity, radius, and temperature as given in Exercise 18.47. Figure 18.15 Schematic HR Diagram for Many Stars. Ninety percent of all stars on such a diagram fall along a narrow band called the main sequence. A minority of stars are found in the upper right; they are both cool (and hence red) and bright, and must be giants. Some stars fall in the lower left of the diagram; they are both hot and dim, and must be white dwarfs. Figure 18.14 HR Diagram for a Selected Sample of Stars. In such diagrams, luminosity is plotted along the vertical axis. Along the horizontal axis, we can plot either temperature or spectral type (also sometimes called spectral class). Several of the brightest stars are identified by name. Most stars fall on the main sequence.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_forwardAccording 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_forward
- We can estimate the masses of most of the stars in Appendix J from the mass-luminosity relationship in Figure 18.9. However, remember this relationship works only for main sequence stars. Determine which of the first 10 stars in Appendix J are main sequence stars. Use one of the figures in this chapter. Make a table of stars’ masses. Figure 18.9 Mass-Luminosity Relation. The plotted points show the masses and luminosities of stars. The three points lying below the sequence of points are all white dwarf stars.arrow_forwardAutomobiles are often used as an analogy to help people better understand how more massive stars have much shorter main-sequence lifetimes compared to less massive stars. Can you explain such an analogy using automobiles?arrow_forwardDescribe how the mass, luminosity, surface temperature, and radius of main-sequence stars change in value going from the “bottom” to the “top” of the main sequence.arrow_forward
- The sketch below shows an H-R diagram for a star cluster. Consider the star to which the arrow points. How is it currently generating energy? Temperature A. by hydrogen shell burning around an inert helium core B. by gravitational contraction C. by core hydrogen fusion D.by core helium fusion combined with hydrogen shell burning E. by both hydrogen and helium shell burning around an inert carbon core Luminosity -→arrow_forwardOne way to calculate the radius of a star is to use its luminosity and temperature and assume that the star radiates approximately like a blackbody. Astronomers have measured the characteristics of central stars of planetary nebulae and have found that a typical central star is 16 times as luminous and 20 times as hot (about 110,000 K) as the Sun. Find the radius in terms of the Sun’s. How does this radius compare with that of a typical white dwarf?arrow_forwardQuestion 41 .Suppose you are looking at H-R diagrams of two similar star clusters. The most luminous main sequence stars in the Porcini cluster are much more luminous than the most luminous main sequence stars in the Morel cluster. What can you conclude? O the Porcini cluster is younger than the Morel cluster O the Porcini cluster is farther away than the Morel cluster O the Porcini cluster is lower in metallicity than the Morel cluster O the Porcini cluster is larger in diameter than the Morel clusterarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
AstronomyPhysicsISBN:9781938168284Author:Andrew Fraknoi; David Morrison; Sidney C. WolffPublisher:OpenStax
Foundations of Astronomy (MindTap Course List)PhysicsISBN:9781337399920Author:Michael A. Seeds, Dana BackmanPublisher:Cengage Learning
Stars and Galaxies (MindTap Course List)PhysicsISBN:9781337399944Author:Michael A. SeedsPublisher:Cengage Learning
Astronomy
Physics
ISBN:9781938168284
Author:Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher:OpenStax
Foundations of Astronomy (MindTap Course List)
Physics
ISBN:9781337399920
Author:Michael A. Seeds, Dana Backman
Publisher:Cengage Learning
Stars and Galaxies (MindTap Course List)
Physics
ISBN:9781337399944
Author:Michael A. Seeds
Publisher:Cengage Learning