21st Century Astronomy
6th Edition
ISBN: 9780393428063
Author: Kay
Publisher: NORTON
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Chapter 21, Problem 26QP
To determine
The significance of CMB displaying black body spectrum.
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[6/2, 7:18 AM] Ali Diaa: Telescopes are an essential tool for astronomers to study the universe. You plan to build yourown telescope that can resolve the Great Red Spot on the surface of Jupiter at a wavelength of600 nm. The farthest distance between the Earth and Jupiter is 968 × 106 km and the Great RedSpot has currently a diameter of 16,500 km.(a) Use the Rayleigh criterion to determine the diameter of the lens’ aperture of your telescopethat is needed to resolve the Great Red Spot on Jupiter.[6/2, 7:44 AM] Ali Diaa: Scientists are developing a new space cannon to shoot objects from the surface of the Earth directly into a low orbit around the Earth. For testing purposes, a projectile is fired with an initialvelocity of 2.8 km/s vertically into the sky.Calculate the height that the projectile reaches, ...(a) assuming a constant gravitational deceleration of 9.81 m/s2.(b) considering the change of the gravitational force with height.Note: Neglect the air resistance for this problem.…
Assuming stars to behave as black bodies stefan-boltzmann law to show that the luminosity of a star is related to its surface temperature and size in the following way:
L = 4(3.14)R^2oT^4
where o= 5.67 ×10^-8 Wm^-2 K-4 is the stefan- boltzmann constant. Then use this expression together with the knowledge that the sun has a surface temperature of 5700k and radius 695 500km to calculate the luminosity of the Sun in units of Watts
Calculate the Eddington limit for star of 103⁰ Msun.
Chapter 21 Solutions
21st Century Astronomy
Ch. 21.1 - Prob. 21.1CYUCh. 21.2 - Prob. 21.2CYUCh. 21.3 - Prob. 21.3ACYUCh. 21.3 - Prob. 21.3BCYUCh. 21.4 - Prob. 21.4CYUCh. 21 - Prob. 1QPCh. 21 - Prob. 2QPCh. 21 - Prob. 3QPCh. 21 - Prob. 4QPCh. 21 - Prob. 5QP
Ch. 21 - Prob. 6QPCh. 21 - Prob. 7QPCh. 21 - Prob. 8QPCh. 21 - Prob. 9QPCh. 21 - Prob. 10QPCh. 21 - Prob. 11QPCh. 21 - Prob. 12QPCh. 21 - Prob. 13QPCh. 21 - Prob. 14QPCh. 21 - Prob. 15QPCh. 21 - Prob. 16QPCh. 21 - Prob. 17QPCh. 21 - Prob. 18QPCh. 21 - Prob. 19QPCh. 21 - Prob. 20QPCh. 21 - Prob. 21QPCh. 21 - Prob. 23QPCh. 21 - Prob. 24QPCh. 21 - Prob. 25QPCh. 21 - Prob. 26QPCh. 21 - Prob. 27QPCh. 21 - Prob. 28QPCh. 21 - Prob. 29QPCh. 21 - Prob. 30QPCh. 21 - Prob. 31QPCh. 21 - Prob. 32QPCh. 21 - Prob. 33QPCh. 21 - Prob. 34QPCh. 21 - Prob. 35QPCh. 21 - Prob. 36QPCh. 21 - Prob. 37QPCh. 21 - Prob. 38QPCh. 21 - Prob. 39QPCh. 21 - Prob. 40QPCh. 21 - Prob. 41QPCh. 21 - Prob. 42QPCh. 21 - Prob. 43QPCh. 21 - Prob. 44QPCh. 21 - Prob. 45QP
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- What would the wavelength of the 21 cm line be for a source moving away from the Earth at 10% the speed of light? What is the source of this 21 cm line?arrow_forward1.2 1.0 0.8 0.6 Cosmic background data from COBE 0.4 0.2 0.0 0.5 10 Wavelength A in mm c) Background (CMB) undertaken by the COBE satellite. Use this diagram to estimate the current temperature of the CMB. Based on your estimate, what would the temperature of the CMB have been at a redshift of z = 5000? The left hand diagram above shows the results from observations of the Cosmic Microwave Radiated Intensity per Unit Wavelength (16° Watts/m per mm)arrow_forwardThe redshift measurements of spectra from magnesium and iron are important in understanding distant galaxies. What are the Kα and Lα wavelengths for magnesium and iron?arrow_forward
- The Andromeda Galaxy, M31, is the closest large spiral galaxy to our Milky Way. When we look at its chemical spectrum, we see that its hydrogen alpha emission line (Hα) has an observed wavelength of λobs = 655 nm.-Calculate z, being careful with the sign.-How fast is it moving in km/s?-Is it redshifted or blueshifted? Is it moving towards or away from us? answer to three significant figures.arrow_forwardWhat is the most likely range of values for Hubble’s constant? What are the uncertainties in its value?arrow_forwardThe Blue hydrogen line has a frequency of 6.90 x 1014 Hz. What will be the observed wavelength of the blue line of a galaxy that is moving away from Earth at 0.4c?arrow_forward
- why is it difficult to measure the Hubble constant?arrow_forwardWhy is it difficult to determine where cosmic rays come from?arrow_forwardThe CMB contains roughly 400 million photons per m3. The energy of each photon depends on its wavelength. Calculate the typical wavelength of a CMB photon. Hint: The CMB is blackbody radiation at a temperature of 2.73 K. According to Wien’s law, the peak wave length in nanometers is given by max=3106T . Calculate the wavelength at which the CMB is a maximum and, to make the units consistent, convert this wavelength from nanometers to meters.arrow_forward
- An AGN hosts a central Black Hole of mass 2×1038×1038 kg. The AGN emits at 1/51/5 of the Eddington limit. Find the luminosity of the AGN. Give your answer in Watts to 3 significant figures.arrow_forwardThe Sun as seen from Earth has an apparent magnitude of -26 in the B-band.1. What would its apparent magnitude be as seen from Jupiter? (Jupiter is approximately 5.2 AU from theSun.)2. At a certain distance d from a Star A, its apparent brightness is f. If we were to travel at a relativisticvelocity to a point in space which is 5 times further away, how much fainter would the star appear to us?(i.e. what fraction of its original apparent brightness would it now appear to us?)arrow_forwardQuestion 2: apparent magnitude my 1 = 305.9, b = −44.9 and is d=4.5 kpc from the Sun. a.) The integrated light from the Milky Way globular cluster NGC 104 has an 4.03 mag and absolute magnitude My -9.52 mag. It is located at b.) = = Estimate the amount of extinction between the Sun and 47 Tucanae in magnitudes. What does this value of extinction mean for the amount of attenuation by dust between Earth and NGC 104?.arrow_forward
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