Concept explainers
(a)
The age of the universe.
Answer to Problem 21Q
The age of the universe is
Explanation of Solution
Given:
The value of the Hubble’s constant
The value of the Hubble’s costant
The value of the Hubble’s costant
Formula used:
The life of the universe is given by,
Calculation:
The life of the universe is calculated by,
Solve further,
Solve further,
Conclusion:
The age of the universe is
(b)
The age of the universe.
Answer to Problem 21Q
The age of the universe is
Explanation of Solution
Formula used:
The life of the universe is given by,
Calculation:
The life of the universe is calculated by,
Solve further,
Solve further,
Solve further,
Conclusion:
The age of the universe is
(c)
The age of the universe and how the age of globular cluster is used to place the limit on the maximum value of Hubble’s constant.
Answer to Problem 21Q
The age of the universe is
Explanation of Solution
Formula used:
The life of the universe is given by,
Calculation:
The life of the universe is calculated by,
Solve further,
Solve further,
Solve further,
Conclusion:
The age of the universe is
The age of the universe is decreasing as the value of the Hubble’s constant is increasing. Since. the age of the globular cluster cannot be less than the universe, as it is not possible that consist of the universe is older than the universe. So the age of the universe is more than the globular cluster and it apply the maximum limit on the value of the Hubble’s constant.
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Chapter 25 Solutions
Universe: Stars And 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 does the term Hubble time mean in cosmology, and what is the current best calculation for the Hubble time?arrow_forwardIf a galaxy is 8.8 Mpc away from Earth and recedes at 498 km/s, what is H0 (in km/s/Mpc)? _______ km/s/Mpc What is the Hubble time (in yr)? _______ yr How would acceleration change your answer? A: If the expansion of the Universe has been accelerating, the Universe could be substantially younger than the value entered above. B: If the expansion of the Universe has been accelerating, the Universe could be substantially older than the value entered above.arrow_forward
- A new astronomical measurement suggests that the Hubble constant is 51 kilometers per second per Megaparsec. If this measurement is correct, what would the Hubble time be in units of years? Is this a plausible value based on other astronomical evidence? Why or why not?arrow_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_forwardA galaxy's rotation curve is a measure of the orbital speed of stars as a function of distance from the galaxy's centre. The fact that rotation curves are primarily flat at large galactocen- tric distances (vrot(r) ~ constant) is the most common example of why astronomer's believe dark matter exists. Let's work out why! Assuming that each star in a given galaxy has a circular orbit, we know that the accelera- tion due to gravity felt by each star is due to the mass enclosed within its orbital radius r and equal to v?/r. Here, ve is the circular orbit velocity of the star. (a) Show that the expected relationship between ve and r due to the stellar halo (p(r) xr-3.5) does not produce a flat rotation curve. (b) Show that a p(r) ∞ r¯² density profile successfully produces a flat ro- tation curve and must therefore be the general profile that dark matter follows in our galaxy.arrow_forward
- What would be the Hubble constant if the universe were 18 billion years old?arrow_forwardPretend that galaxies are spaced evenly, 7.0 Mpc apart, and the average mass of a galaxy is 1.0 ✕ 1011 M. What is the average density (in kg/m3) of matter in the universe? (Note: The volume of a sphere is 4/3pieR^3 and the mass of the sun is 2.0 ✕ 1030 kg.) ______ kg/m^3 Which model universe does this density value support? A: open B: flat C: closedarrow_forward= 2. Using a Hubble constant of Ho 70 km/s/Mpc, find the distance to the galaxy cluster that moves with a velocity of 6500 km/s. Give your answer in megaparsecs and light-years.arrow_forward
- Calculate the age of the universe if the Hubble constant were 65 km/s/Mpc.arrow_forwardIf a galaxy is 8.9 Mpc away from Earth and recedes at 497 km/s, what is H. (in km/s/Mpc)? km/s/Mрс What is the Hubble time (in yr)? years How old (in yr) would the universe be, assuming space-time is flat and the expansion of the universe has not been accelerating? years How would acceleration change your answer? If the expansion of the Universe has been accelerating, the Universe could be substantially younger than the value entered above. If the expansion of the Universe has been accelerating, the Universe could be substantially older than the value entered above.arrow_forwardHow would I calculate the age of the universe in billions of years from the Hubble constant (73.48 +/- 1.66 km/s/Mpc)? I know I need to use basic unit conversion but I’m not sure which numbers to use.arrow_forward
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