Concept explainers
(a)
The volume of the disk in cubic parsecs if the diameter of the disk is about
Answer to Problem 46Q
Volume of the disk in cubic parsecs =
Explanation of Solution
Given data:
Diameter of the disk =
Thickness of the disk =
Formula used:
Calculation:
Conclusion:
The volume of the disk in cubic parsecs =
(b)
The volume in cubic parsecs of a sphere with a radius of
Answer to Problem 46Q
Volume in cubic parsecs of a sphere with a radius of
Explanation of Solution
Given data:
Radius of the sphere centered on the sun =
Formula used:
Calculation:
Conclusion:
Volume in cubic parsecs of a sphere with a radius of
(c)
The probability of a supernova occurring within
The probability for one should expect to see supernovae within 300 pc of the Sun given that there are about 3 supernovae each century in our galaxy
Answer to Problem 46Q
Probability of a supernova occurring within
Time on average per century one should expect to see supernovae within 300 pc of the sun =
Explanation of Solution
Given data:
The radius of the sphere centered on the sun =
Number of supernovas occurring for a single century =
Formula used:
Calculation:
The probability that a supernova occurs within 300 pc of the Sun
Time on average per century, one should expect to see a supernova within 300 pc of the Sun
Conclusion:
Probability of a supernova occurring within
Time on average per century one should expect to see a supernova within 300 pc of the sun =
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Chapter 22 Solutions
UNIVERSE (LOOSELEAF):STARS+GALAXIES
- If 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_forwardWhat 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_forwardThe Kormendy relation for ellipticals can be written as He = 20.2+ 3.0 log R. where R. is the half-light radius (in kpc) and 4e is the surface brightness (in magnitudes per square arc second) at R.. An elliptical galaxy obeying this relation will have a total luminosity Lo R for some index 7. What is the correct value of n? O a. n=-6/5 O b. n= 4/5 T23D Oc n= 16/5 O d. n cannot be determined with the information we have.arrow_forward
- Consider a Schechter luminosity function of the form where a = 0.9, ΦΣ = -0 (L)dL = D(+) L e-(L/Lx)dL, L 0.012h3 Mpc3 and L - 1010h Lo. Calculate the total number density. Express the final answer in terms of h where h = Ho/(100 km s−¹Mpc¯¹) (Ho is the Hubble constant).arrow_forwardSuppose a quasar is shining with a luminosity L. What is the approximate minimal mass of the black hole? (If the black hole had a lower mass than this, the pressure in the material would overcome the gravity of the black hole and the material would be blown apart.) Give your answer in solar masses, in scientific notation to one significant figure (no decimal places). Value: L=1×10^12Lsun Suppose the quasar in the previous problem is 10% efficient at turning rest mass into energetic photons, according to Einstein's equation E=mc2. What is the necessary rate of accretion of mass onto this black hole, to sustain its luminosity of 1* 1012 solar luminosities -- i.e. how much mass must be 'fed' to this black hole to keep the AGN shining so brightly? Give your response in units of solar masses of material per year, with one decimal place.arrow_forwardQuestion 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_forward
- Consider the Milky Way disk, which has a 50 kpc diameter and a total height of 600 pc. Suppose that the Sun orbits precisely at the mid-plane of the disk in a circular orbit. Supernovae explosions happen randomly throughout the disk at a rate of about 2 per 100 years. Consider a spherical region around the Sun with a radius of 300 pc. Ignore the Milky Way bulge and halo in this problem; assume the Milky Way disk is perfectly uniform and extends all the way through the region of the bulge. (I.e., the Milky Way is modeled *only* as a cylindrical disk--like a hockey puck-- with constant density throughout.) If a particular supernova goes off at a random location within the disk, what is the probability that it went off in the 300 pc radius spherical region near the Sun? Express your probability as a percentage (but without writing the percent sign). [Hint: there is a 100% probability that the supernova went off somewhere in the volume of the Milky Way disk; there is a 50% probability that…arrow_forwardAnalyzing the spectrum of a distant galaxy, you discover evidence that a type la supernova is occurring in that galaxy. A type la supernova has a peak luminosity of about 1010 solar luminosities (1 solar luminosity = 3.8e26 Watts). Looking at an image of the galaxy, you estimate that here on earth your telescope only sees a brightness of 8.45E-10 Watts/m². Using this information and the brightness equation, how distant is the galaxy in which the supernova is occurring? Give your answer in It yrs.arrow_forwardAssume that the average galaxy contains 1011 MSun and that the average distance between galaxies is 10 million light-years. Calculate the average density of matter (mass per unit volume) in galaxies. What fraction is this of the critical density, 9.6 * 10-27?arrow_forward
- Our galaxy is approximately 100,000 light years in diameter and 2,000 light years thick through the plane of the galaxy. If we were to compare the ratio of the diameter galaxy and its thickness to the ratio of the diameter of a CD and its thickness (CD has a diameter of 12 cm and thickness of 0.6 mm), what would be the factor differentiating those ratios? Put differently, if the galaxy were scaled down to the diameter of a CD, how many times thicker or thinner would the galaxy be than the CD? (For example if it would be twice as thick, you would answer 2 and if it were twice as thin you would answer 0.5 (aka 1/2))arrow_forwardThe best parallaxes obtained with the Hipparcos satellite have an uncertainty such that we believe measurements as low as 0.005 arc-seconds. What is the farthest distance a star can be to have an accurate distance from Hipparcos? 200 Parsecs The disk of our Galaxy is 100,000 light-years in diameter. Using the results from the previous problem, what fraction of the diameter of the Galaxy's disk is the distance for which we can measure accurate parallaxes? 0.0065 The Gaia satellite has greatly improved precision over Hipparcos, measuring parallaxes that are as small as 0.00025 arcseconds. How many times farther away is Gaia be able to measure distances to than Hipparcos?arrow_forwardThe best parallaxes obtained with the Hipparcos satellite have an uncertainty such that we believe measurements as low as 0.005 arc-seconds. What is the farthest distance a star can be to have an accurate distance from Hipparcos?200 parsecs The disk of our Galaxy is 100,000 light-years in diameter. Using the results from the previous problem, what fraction of the diameter of the Galaxy's disk is the distance for which we can measure accurate parallaxes?arrow_forward
- Foundations of Astronomy (MindTap Course List)PhysicsISBN:9781337399920Author:Michael A. Seeds, Dana BackmanPublisher:Cengage Learning