The cosmic microwave background consists of: huge clouds of dark matter interspersed with equally huge clouds of H and He enormous cold voids separating warmer filaments of young protostas and protogalaxies denser areas of slightly warmer Hydrogen mixed with slightly less dense areas of slightly cooler Helium an enormous number of photons, particles of light that emerged after the Big Bang atoms of H and He, dark matter, and an immense amount of energy MacBook Air DII DD 30 D00 000 F7 F8 F9 F4 F5 F6

The cosmic microwave background consists of: huge clouds of dark matter interspersed with equally huge clouds of H and He enormous cold voids separating warmer filaments of young protostas and protogalaxies denser areas of slightly warmer Hydrogen mixed with slightly less dense areas of slightly cooler Helium an enormous number of photons, particles of light that emerged after the Big Bang atoms of H and He, dark matter, and an immense amount of energy MacBook Air DII DD 30 D00 000 F7 F8 F9 F4 F5 F6

Stars and Galaxies

9th Edition

ISBN:9781305120785

Author:Michael A. Seeds, Dana Backman

Publisher:Michael A. Seeds, Dana Backman

Chapter16: Galaxies

Section: Chapter Questions

Problem 3DQ

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The Milky Way grew through merging with many smaller galaxies. What are the observational signatures of this process? O The motion of old stars in the bulge and halo of our galaxy are randomly orientated, meaning they were formed from collisions of small, accreted, galaxies all on different paths. O The ordered motion of the bulge / halo stars means that they came from many objects. The random motions of stars in the disk means it was formed from collisions of small, accreted, galaxies. O The motion of young stars in the disk are all in the same direction, meaning they came in as seperate objects.
Assume that the umber density of stars in the Milky Way is 0.14 pc-3. There are 10" stars uniformly distributed across the galaxy. Also assume that there is one supernova every 30 years and all of them have same luminosity. Find the probablity, P, of a supernova causing extinction on Earth in total life span of the Sun.
What do you mean by weakly interacting massive particles, or WIMPs,?
Suppose the Hubble constant were not 22 but 12.1 km/s per million light-years. Then what would the critical density (in kg/m³) be? (For H = 22 km/s per million light-years, the critical density is 9.6 x 10-27 kg/m³.) kg/m³1 I Ih SAMSUNG
I'm doing a debate about Kalam cosmological. I need to have an example of something out of nothing (Or maybe we can't prove the cause)? Can you help give 5 modern physics example?
Assume that the number density of stars in the Milky Way is 0.14 pc-3. (e) There are 10" stars uniformly distributed across the galaxy. Also assume that there is one supernova every 30 years and all of them have same luminosity. Find the probablity, P, of a supernova causing extinction on Earth in total life span of the Sun.
Assume a flat FRW universe, dominated by radiation throughout its history. Calculate the physical, cosmological horizon size at t=t_0 The initial conditions for the scale factor are a=a_0 at t=t0(today). Which asnwer is correct; a)R_H=2a_0ct_0 b) R_H = 3a_0ct_0 c)R_H = ct_0 d) R_H=2ct_0
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…
It is possible to derive the age of the universe given the value of the Hubble constant and the distance to a galaxy, again with the assumption that the value of the Hubble constant has not changed since the Big Bang. Consider a galaxy at a distance of 400 million light-years receding from us at a velocity, v. If the Hubble constant is 20 km/s per million light-years, what is its velocity? How long ago was that galaxy right next door to our own Galaxy if it has always been receding at its present rate? Express your answer in years. Since the universe began when all galaxies were very close together, this number is a rough estimate for the age of the universe.
(a) Calculate The approximate age of the universe from the average value of the Hubble constant, To do this, calculate the time it would take to travel 1 Mly at a constant expansion rate of 20 km/s. (b) If deceleration is taken into account, would the actual age of the universe be greater or less than that found here? Explain.
What evidence can you give that we live in a galaxy?
We have said repeatedly that blue light undergoes more extinction than red light, which is true for visible and shorter wavelengths. Is the same true for X-rays? Look at Figure 20.19. The most dust is in the galactic plane in the middle of the image, and the red color in the image corresponds to the reddest (lowestenergy) light. Based on what you see in the galactic plane, are X-rays experiencing more extinction at redder or bluer colors? You might consider comparing Figure 20.19 to Figure 20.14. Figure 20.14 Barnard 68 in Infrared. In this image, we see Barnard 68, the same object shown in Figure 20.9. The difference is that, in the previous image, the blue, green, and red channels showed light in the visible (or very nearly visible) part of the spectrum. In this image, the red color shows radiation emitted in the infrared at a wavelength of 2.2 microns. Interstellar extinction is much smaller at infrared than at visible wavelengths, so the stars behind the cloud become visible in the infrared channel. (credit: ESO) Figure 20.19 Sky in X-Rays. This image, made by the ROSAT satellite, shows the whole sky in X-rays as seen from Earth. Different colors indicate different X-ray energies: red is 0.25 kiloelectron volts, green is 0.75 kiloelectron volts, and blue is 1.5 kiloelectron volts. The image is oriented so the plane of the Galaxy runs across the middle of the image. The ubiquitous red color, which does not disappear completely even in the galactic plane, is evidence for a source of X-rays all around the Sun. (credit: modification of work by NASA)