Concept explainers
Assume that the Sun orbits the center of the Galaxy at a speed of 220 km/s and a distance of 26,000 lightyears from the center.
A. Calculate the circumference of the Sun’s orbit, assuming it to be approximately circular. (Remember that the circumference of a circle is given by 2pR, where R is the radius of the circle. Be sure to use consistent units. The conversion from light-years to km/s can be found in an online calculator or appendix, or you can calculate it for yourself: the speed of light is 300,000 km/s, and you can determine the number of seconds in a year.)
B. Calculate the Sun’s period, the “galactic year.” Again, be careful with the units. Does it agree with the number we gave above?
Want to see the full answer?
Check out a sample textbook solutionChapter 25 Solutions
Astronomy
Additional Science Textbook Solutions
College Physics: A Strategic Approach (4th Edition)
Conceptual Physical Science (6th Edition)
College Physics
The Cosmic Perspective Fundamentals (2nd Edition)
College Physics (10th Edition)
Essential University Physics: Volume 1 (3rd Edition)
- I answer is not 100, I also tried 21. I need help! Thank you!arrow_forwardA galaxy with a spherically symmetric distribution of matter has a mass density profile of the type p(r) ∞ 1/r, where r is the radial coordinate from the centre of the galaxy. To what type of circular velocity (r) does this correspond? Select one: a. (r) O b. c. O d. (r) ~ r (r) ~ √r (r): = constantarrow_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
- I attempted to answer this question and I'm not sure what I am doing wrong. My formula says A.S. = 206265 (separation/distance from observer) I know to convert to the same units, so I ended up with 80 Million Km being 8 x 10 ^ -6 LY Could you please explain each step especially for the part that I got wrong for both A and B?arrow_forward1. A distant galaxy has an apparent magnitude of 10 and is 4,000 kpc away. What is its absolute magnitude? (Round your answer to at least one decimal place.) The difference in absolute magnitude between two objects viewed from the same distance is related to their fluxes by the flux-magnitude relation. FA/FB= 2.51(MB − MA) 2. How does the absolute magnitude of this galaxy compare to the Milky Way (M = −21)?arrow_forwardhelparrow_forward
- For 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_forwardQuestion 5B pleasearrow_forwardQuestion A1 a) The Large Magellanic Cloud (LMC) is a galaxy in the vicinity of the Milky Way. It is at a distance of 50 kpc, and has a size across of 9.86 kpc. Consider a star similar to Vega (absolute magnitude M = 0.58) which is at the edge of the LMC as seen on the sky. What is its apparent magnitude? Show your calculation. b) A second similar star is observed near the centre of the LMC as seen on the sky with an observed apparent magnitude of m = 20.3. Is this consistent with the star being a member of the LMC? Explain your reasoning. c) An observational study has derived a map of the extinction Ay across the LMC, and shown that its average value is 0.38, with a standard deviation of 0.57. For the star discussed in part (b), if extinction is taken into account, does your conclusion about the star's membership of the LMC change? Explain your reasoning. You may assume that the star may suffer the full (positive) range of extinction found in the study of the LMC. d) Which other…arrow_forward
- Estimating the mass of the Milky Way a) Assuming the Sun moves in a circular orbit of radius 8 kiloparsecs around the center of the Milky Way, and that its orbital speed is 220 km/s, calculate how many years it takes the Sun to complete one orbit of the Galaxy. Remember to convert kiloparsecs to kilometers. b) Using the modified form of Kepler's third law (introduced in Lecture 13, for measuring the combined masses of binary stars), R³ m+ M = estimate the mass of the Milky Way enclosed within 8 kpc (Sun's orbit radius). The mass of the Milky Way inside p² I the Sun's orbit can be represented as a single mass (M) located at its center, and the mass of the Sun (m) can be considered infinitesimally small compared to the Milky Way's (i.e., m < M). c) Is this estimate of the Milky Way's mass an upper or lower limit? Explain your reasoning.arrow_forwardApproximate 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_forwardFor 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.arrow_forward
- AstronomyPhysicsISBN:9781938168284Author:Andrew Fraknoi; David Morrison; Sidney C. WolffPublisher:OpenStaxStars and Galaxies (MindTap Course List)PhysicsISBN:9781337399944Author:Michael A. SeedsPublisher:Cengage LearningPhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
- Foundations of Astronomy (MindTap Course List)PhysicsISBN:9781337399920Author:Michael A. Seeds, Dana BackmanPublisher:Cengage LearningPhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning