What would be the critical density of matter in the universe if the value of the Hubble constant were (a) 40 km/sec/ Mpc? (b) 90 km/sec/Mpc?

Q: How would I calculate the age of the universe in billions of years from the Hubble constant (73.48…

A: Everything that exists resides in the universe, including the Earth, planets, stars, space, and…

Q: If a quasar has a recessional velocity of 2.7 × 10 5 km/sec and is determined to be 3600 Mpc, what…

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Q: Estimate the age of the universe for a Hubble constant of (a)50km/s/Mpc, (b) 75km/s/Mpc, and (c) 100…

A: The Hubble time is t = 1/H0 . For each value of Ho, we have: a). t = 6.18 × 10¹⁷ s = 1.96 × 1010 yrs…

Q: e gravitational energy of a pair of colliding galaxies , each of mass 10 Mo separated by a distance…

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Q: Imagine that an observed distant galaxy is measured to have a distance of 40 Mpc by a Type Ia…

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Q: Consider a universe where Big Bang nucleosynthesis produced significantly more 4He than 1H. Estimate…

A: We have to Consider a universe where Big Bang nucleosynthesis produced significantly more 4He than…

Q: What is the redshift z of a galaxy 193 Mpc away from us?   Note: Assume a value of the Hubble…

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Q: Suppose the Hubble constant were not 22 but 12.1 km/s per million light-years. Then what would the…

A: Write the expression for the volume of the sphere. Write the expression for the mass. Here, ρ is…

Q: What Hubble constant corresponds to an approximate age of the universe of 1010 y? To get an…

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Q: If a galaxy is 9.2 Mpc away from Earth and recedes at 475 km/s, what is H0 (in km/s/Mpc)?

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Q: Recall that Hubbleʹs law is written v = H0d, where v is the recession velocity of a galaxy located a…

A: Given data: Hubble's constant (H0) = 80 km/s/Mpc Distance (d) = 800 Mpc Required: Recession velocity…

Q: The CMB contains roughly 400 million photons per m³. The energy of each photon depends on its…

A: The wavelength is 0.0011 m. The energy of a photon is 1.807×10-22 J.

Q: Suppose the Hubble constant were not 22 but 53 km/s per million light-years. Then what would the…

A: Given: New Hubble constant, H' = 53 km/s per million light-years

Q: Recall that Hubbleʹs law is written v = H0d, where v is the recession velocity of a galaxy located a…

A: Data provided: H0 = 80 km/Mpc Distance (d) = 800 Mpc Required: Velocity of the galaxy (v)

Q: The CMB contains roughly 400 million photons per m³. The energy of each photon depends on its…

A: Mass = E/c2

Q: In the Benchmark Model, what is the total mass of all the matter within the current Hubble Radius…

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Q: why are the shells visible around some elliptical galaxies significant?

A: The shell structures in the elliptical galaxies indicates the extremely low surface brightness and…

Q: An electron jumps from n=3 to n=2 in a hydrogen atom in a distant galaxy, emitting light. If we…

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Q: Why aren’t the fluctuations there in the formation of Galaxies and other similar entities?

A: Galaxies and the other similar entities could not be without the existence of fluctuations in the…

Q: A certain galaxy is observed to be receding from the Sun at a rate of 8000 km/sec. The distance to…

A: According to the Hubble's law, the value of the Hubble constant is, v=HdH=vd Here, H is the Hubble's…

Q: If the average density of the Universe is small compared with the critical density, the expansion of…

A: According to Hubble’s law v = HR The expression for R  is R=vΔt Thus, v=HvΔtΔt=1H Here, ∆t is the…

Q: An astronomer observed the motions of some galaxies. Based on his observations, he made the…

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Q: If Hubble’s constant is taken to be 70 km/sec/Mpc, and a quasar is found with a radial velocity of…

A: Given data: The Hubble’s constant is H0=70 km/sec/Mpc. The radial velocity is v=0.95c.

Q: 46 Figure 44-12 is a hypothetical plot of the recessional speeds v of galaxies against their…

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Q: Pretend that galaxies are spaced evenly, 7.0 Mpc apart, and the average mass of a galaxy is 1.0 ✕…

A: The average density of matter in the universe is given by

Q: How does Hubble’s Constant depend on time? How about distance? (In what sense is it constant?

A: Given: How does Hubble’s Constant depend on time? How about distance? (In what sense is it…

Q: If a galaxy is 18 Mpc from Earth and the Hubble constant is 70 km/s/Mpc, what is the recession…

A: Answer:-  Answer (1)  Given  Distance (d) = 18 Mpc  Hubble constant (Ho) = 70 km/s/Mpc  Velocity of…

Q: According to the standard Big Bang theory (neglecting any effects of cosmic acceleration), what is…

A: Hubble constant = 50 km/s/Mpc age of universe = inverse of hubble constant  = 1/(50 km/s/Mpc ) Using…

Q: In the reading, you were told that there were roughly 10,000 galaxies in the image of the Hubble…

A: Given:  one image of hubble ultra deep field is roughly 10 square arcminutes.  Number of galaxies in…

Q: The red-shift of a galaxy observed by us corresponds to a speed of 50000 km/s. How far is the galaxy…

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Q: why is it difficult to measure the Hubble constant?

A: Hubble’s constant is used to find and describe the expansion of universe. Edwin Hubble, the American…

Q: What is Hubble constant?

A: Introduction: Hubble constant is the constant of proportionality of the relative velocity of the…

Q: The mass density of our universe is measured to be about 10-29 kg/m3. If an arbitrary point is…

A: mass density of our universe is measured to be about 10-29 kg/m3. If an arbitrary point is chosen as…

Q: Suppose you have obtained spectra of several galaxies and have measuerd the observed wavelength of…

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Q: The density of the universe is   a. equal to the critical density if the universe is closed.   b.…

A: Critical density is the average density of matter required for the universe to just halt it's…

Q: If Hubble’s law can be extrapolated to very large distances, at what distance would the apparent…

A: The equation for the distance at which the apparent recessional speed equals the speed of light is

Q: The Hubble Law, equation (D), can be used to determine the age of the universe. Using your average…

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Q: The temperature of the CMB today is T=2.725 K. Calculate the temperature of the CMB at redshift…

A: present temperature of CMB , To = 2.725 K temperature to be calculated at redshift of , z=2000

Stellar evolution

We may see thousands of stars in the dark sky. Our universe consists of billions of stars. Stars may appear tiny to us but they are huge balls of gasses. Sun is a star of average size. Some stars are even a thousand times larger than the sun. The stars do not exist forever they have a certain lifetime. The life span of the sun is about 10 billion years. The star undergoes various changes during its lifetime, this process is called stellar evolution. The structure of the sun-like star is shown below.

Red Shift

It is an astronomical phenomenon. In this phenomenon, increase in wavelength with corresponding decrease in photon energy and frequency of radiation of light. It is the displacement of spectrum of any kind of astronomical object to the longer wavelengths (red) side.