Concept explainers
(a)
The volume of the disk in cubic parsecs if the diameter of the disk is 50 kpc and thickness is 600 pc.
(a)
Answer to Problem 46Q
Solution:
The volume is
Explanation of Solution
Given data:
The diameter of the disk is 50 kpc and its thickness is 600 pc.
Formula used:
The expression for volume of a disk is:
Here
Explanation:
Recall the formula for volume of a disk.
Substitute 50,000 pc for
Conclusion:
The volume of the disk is
(b)
The volume of a sphere of radius 300 pc orbiting the Sun.
(b)
Answer to Problem 46Q
Solution:
The volume is
Explanation of Solution
Given data:
The radius of the sphere is 300 pc.
Formula used:
The expression for volume of a sphere is:
Here
Explanation:
Recall the expression for volume of a sphere.
Substitute 300 pc for
Conclusion:
The volume of sphere is
(c)
The probability of a supernova within the radius of the Sun, that is, 300 pc, if supernovae occur randomly throughout the volume of the galaxy. Also, calculate the time for these explosions if supernovae occur three times in a century.
(c)
Answer to Problem 46Q
Solution:
The probability is
Explanation of Solution
Given data:
The radius of the sun is
Formula used:
The expression to find the number of 300 pc spheres is:
Here
The expression for probability is:
Here
Explanation:
The volume of the sphere of radius
Recall the expression for number of spheres.
Substitute
Recall the expression for probability.
Substitute 11,000 for
If there are three supernovae then their occurrence will be:
Conclusion:
The probability of a supernova within 300 pc is
Want to see more full solutions like this?
Chapter 22 Solutions
Universe
- What is the ratio of the percent of metals in extreme Population I stars (3%) to that in extreme Population II stars (0.05%)? NpopI NpopII =arrow_forwardIf a galaxy contains a supernova that at its brightest has an apparent magnitude of 17, how far away is the galaxy? Assume that the absolute magnitude of the supernova is -19.arrow_forwardA supernova’s energy is often compared to the total energy output of the Sun over its lifetime. Using the Sun’s current luminosity, calculate the total solar energy output, assuming a 1010 year main-sequence lifetime. Using Einstein’s formula E=mc2 calculate the equivalent amount of mass, expressed in Earth masses. [Hint: The total energy output of the Sun over its lifetime is given by its current luminosity times the number of seconds in a year times its ten billion-year lifetime; ; mass of earth = 6×1024kg; c = 3×108m/s. Your answer should be 200-300 Earth masses.]arrow_forward
- Question 3: (a) A Type la supernova is seen to occur in the central bulge of a spiral galaxy. At its peak, the total apparent magnitude of the bulge plus the supernova is V= 13.68. Pre-explosion images reveal the bulge alone to have a magnitude V= 14.21. Assuming that all Type Ia supernova have peak absolute visual magnitudes of My = -19.30, calculate the distance to this galaxy, assuming there is no extinction in the direction of the supernova. (b) Estimate the observed wavelength of the Hẞ line (rest-frame wavelength 486.1 nm) in this galaxy. Assume the Hubble constant has the value 67.4 kms ¹Mpc-¹.arrow_forwardA supernova's energy is often compared to the total energy output of the Sun over its lifetime. Using the Sun's current luminosity, calculate the total solar energy output, assuming a 1010 year main-sequence lifetime. Using Einstein's formula E = mc? calculate the equivalent amount of mass, expressed in Earth masses. [Hint: The total energy output of the Sun over its lifetime is given by its current luminosity times the number of seconds in a year times its ten billion-year lifetime; Week 5 slide 4; mass of earth = 6x1024kg; c = 3x10®m/s. Your answer should be 200-300 Earth masses.]arrow_forwardCalculate the total number density ( ntot ) and the density ( ρ ) at a depth in a star composed of pure hydrogen where T = 9500 K and 35 % of the atoms are ionized (assume UI = 2). What percentage of hydrogen atoms are in the energy level n = 2?arrow_forward
- Would you expect to observe every supernova in our own Galaxy? Why or why not?arrow_forwardThe best parallaxes obtained with Hipparcos have an accuracy of 0.001 arcsec. If you want to measure the distance to a star with an accuracy of 10%, its parallax must be 10 times larger than the typical error. How far away can you obtain a distance that is accurate to 10% with Hipparcos data? The disk of our Galaxy is 100,000 light-years in diameter. What fraction of the diameter of the Galaxy’s disk is the distance for which we can measure accurate parallaxes?arrow_forwardA supernova can eject material at a velocity of 10,000 km/s. How long would it take a supernova remnant to expand to a radius of 1 AU? How long would it take to expand to a radius of 1 light-years? Assume that the expansion velocity remains constant and use the relationship: expansiontime=distanceexpansionvelocity .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_forwardThe Large Magellanic Cloud has about one-tenth the number of stars found in our own Galaxy. Suppose the mix of high- and low-mass stars is exactly the same in both galaxies. Approximately how often does a supernova occur in the Large Magellanic Cloud?arrow_forwardIf the diameter of the Milky Way Galaxys visible disk, 80,000 ly, is represented in a model by a dinner plate with a diameter of 10 inches, what is the model distance to galaxy M31, 2.6 millionly away? What is the model distance to the Virgo galaxy cluster, 16 Mpc away? (Convert answers to feet.)arrow_forward
- AstronomyPhysicsISBN:9781938168284Author:Andrew Fraknoi; David Morrison; Sidney C. WolffPublisher:OpenStaxFoundations 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