Understanding Our Universe
3rd Edition
ISBN: 9780393614428
Author: PALEN, Stacy, Kay, Laura, Blumenthal, George (george Ray)
Publisher: W.w. Norton & Company,
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Question
Chapter 1, Problem 45QAP
To determine
The number of stars in the local group.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
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))
For a circular velocity profile of the type (r) = ar¹
ar1/9, where a is a constant and r is the radial distance from the centre of a spiral galaxy, find the ratio (r)/(r),
where (r) is the epicyclic frequency and 2(r) is the angular velocity. Enter your answer to 2 decimal places.
Suppose you want to observe every galaxy within some distance. Your enterprising assistant says that instead you can observe every galaxy within double the original distance. What is the ratio of the number of galaxies you can now observe as opposed to before?
Chapter 1 Solutions
Understanding Our Universe
Ch. 1.1 - Prob. 1.1CYUCh. 1.2 - Prob. 1.2CYUCh. 1.3 - Prob. 1.3CYUCh. 1 - Prob. 1QAPCh. 1 - Prob. 2QAPCh. 1 - Prob. 3QAPCh. 1 - Prob. 4QAPCh. 1 - Prob. 5QAPCh. 1 - Prob. 6QAPCh. 1 - Prob. 7QAP
Ch. 1 - Prob. 8QAPCh. 1 - Prob. 9QAPCh. 1 - Prob. 10QAPCh. 1 - Prob. 11QAPCh. 1 - Prob. 12QAPCh. 1 - Prob. 13QAPCh. 1 - Prob. 14QAPCh. 1 - Prob. 15QAPCh. 1 - Prob. 16QAPCh. 1 - Prob. 17QAPCh. 1 - Prob. 18QAPCh. 1 - Prob. 19QAPCh. 1 - Prob. 20QAPCh. 1 - Prob. 21QAPCh. 1 - Prob. 22QAPCh. 1 - Prob. 23QAPCh. 1 - Prob. 24QAPCh. 1 - Prob. 25QAPCh. 1 - Prob. 26QAPCh. 1 - Prob. 27QAPCh. 1 - Prob. 28QAPCh. 1 - Prob. 29QAPCh. 1 - Prob. 30QAPCh. 1 - Prob. 31QAPCh. 1 - Prob. 32QAPCh. 1 - Prob. 34QAPCh. 1 - Prob. 35QAPCh. 1 - Prob. 36QAPCh. 1 - Prob. 37QAPCh. 1 - Prob. 38QAPCh. 1 - Prob. 39QAPCh. 1 - Prob. 40QAPCh. 1 - Prob. 41QAPCh. 1 - Prob. 42QAPCh. 1 - Prob. 43QAPCh. 1 - Prob. 44QAPCh. 1 - Prob. 45QAP
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
- Let's say that the number density of galaxies in the universe is, on average, 3 × 10–68 galaxies/m3. If astronomers could observe all galaxies out to a distance of 1010 light-years, how many galaxies would they find? (Note that there are 1016 meters in 1 light-year.)arrow_forwardAssume that a typical galaxy contains about 200 billion stars and that there are more than 150 billion galaxies in the known universe. Estimate the total number of stars in the universe.arrow_forwardFor a circular velocity profile of the type (r) = ar¹/9, where a is a constant and r is the radial distance from the centre of a spiral galaxy, find the ratio K(r)/(r), where K(r) is the epicyclic frequency and 2(r) is the angular velocity. Enter your answer to 2 decimal places.arrow_forward
- Approximate values of length (in meters) 107 Diameter of Earth 1011 Distance from Earth to Sun 1016 Distance traveled by light in one year 1021 Diameter of the Milky Way Galaxy 1022 Distance from Earth to the nearest galaxy 1025 Distance from Earth to the edge of the known universearrow_forwardIn the reading, you were told that there were roughly 10,000 galaxies in the image of the Hubble Ultra Deep Field alone. The image is roughly 10 square arcminutes and there are roughly 1.5*10^8 square arcminutes composing the entire sky. With that in mind and assuming that the Hubble Ultra Deep Field represents an average part of the sky, roughly how many galaxies may exist in the observable universe? (Please include commas for every factor of 1,000; for example 2,343,567,890)arrow_forwardThe Tully-Fischer method relies on being able to relate the mass of a galaxy to its rotation velocity. Stars in the outer-most regions of the Milky Way galaxy, located at a distance of 50 kpc from the galactic centre, are observed to orbit at a speed vrot = 250 km s−1. Using Kepler’s 3rd Law, determine the mass in the Milky Way that lies interior to 50 kpc. Express your answer in units of the Solar mass.arrow_forward
- Astrophysicists estimate that there are about 100 billion galaxies in the universe, and thaton average each galaxy has about 100 billion stars. Comparing this estimate to Archimedes’ estimate, which is larger: the number of stars in the universe, or the number of grains of sand needed to fill a volume the size of the Earth?arrow_forwardSuppose you want to observe every galaxy within some distance. Your enterprising assistant says that instead you can observe every galaxy within double the original distance. What is the ratio of the number of galaxies you can now observe as opposed to before? (For example, if you can observe twice as many: 2. If you can observe half as many: 0.5) Your answerarrow_forwardmathematician Archimedes, responding to a claim that the number of grains of sand was infinite, calculated that the number of grains of sand needed to fill the universe was on the order of 1063. Our understanding of the size of the universe has changed since then, and we now know that the observable universe alone is a sphere with a radius of 1026 m. Estimating the size of a grain of sand, A) Approximately how many grains of sand would fill the observable universe? B) How many times larger or smaller is this number than Archimedes' result?arrow_forward
- Based on your analysis of galaxies in Table 26.1, is there a correlation between the population of stars and the quantity of gas or dust? Explain why this might be.arrow_forwardThe dwarf galaxy in Sagittarius is the one closest to the Milky Way, yet it was discovered only in 1994. Can you think of a reason it was not discovered earlier? (Hint: Think about what else is in its constellation.)arrow_forwardSuppose the average mass of a star in the Galaxy is one-third of a solar mass. Use the value for the mass of the Galaxy that we calculated in Exercise 25.19, and estimate how many stars are in the Milky Way. Give some reasons it is reasonable to assume that the mass of an average star is less than the mass of the Sun.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning
AstronomyPhysicsISBN:9781938168284Author:Andrew Fraknoi; David Morrison; Sidney C. WolffPublisher:OpenStax
Stars and Galaxies (MindTap Course List)PhysicsISBN:9781337399944Author:Michael A. SeedsPublisher:Cengage Learning
Foundations of Astronomy (MindTap Course List)PhysicsISBN:9781337399920Author:Michael A. Seeds, Dana BackmanPublisher:Cengage Learning
Horizons: Exploring the Universe (MindTap Course ...PhysicsISBN:9781305960961Author:Michael A. Seeds, Dana BackmanPublisher:Cengage Learning
Physics for Scientists and Engineers: Foundations...
Physics
ISBN:9781133939146
Author:Katz, Debora M.
Publisher:Cengage Learning
Astronomy
Physics
ISBN:9781938168284
Author:Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher:OpenStax
Stars and Galaxies (MindTap Course List)
Physics
ISBN:9781337399944
Author:Michael A. Seeds
Publisher:Cengage Learning
Foundations of Astronomy (MindTap Course List)
Physics
ISBN:9781337399920
Author:Michael A. Seeds, Dana Backman
Publisher:Cengage Learning
Horizons: Exploring the Universe (MindTap Course ...
Physics
ISBN:9781305960961
Author:Michael A. Seeds, Dana Backman
Publisher:Cengage Learning
General Relativity: The Curvature of Spacetime; Author: Professor Dave Explains;https://www.youtube.com/watch?v=R7V3koyL7Mc;License: Standard YouTube License, CC-BY