Pearson eText -- Physics for Scientists and Engineers with Modern Physics -- Instant Access (Pearson+)
5th Edition
ISBN: 9780137488179
Author: Douglas Giancoli
Publisher: PEARSON+
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Chapter 44, Problem 51GP
To determine
The ratio of the diameter of the two stars that have spectra peaks at
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The relationship between the average luminosity and pulsation period for Cepheid variable stars can be written L = L⊙P3.7, where the period P is measured in days. A cepheid variable is observed in a distant galaxy, and is determined to have a pulsation period of 50 days. The average flux received from this star is measured to be 2.14×10−16Wm−2. Determine the distance to the galaxy and express your answer in units of Mpc.
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
Problem 3:
Two stars, M and N, from the same galaxy (at the same distance from
earth) are observed to have the same luminosity (that is, they emit the
same amount of energy per unit time). Star M is red, its spectrum peaks
2.4 × 1015s-1 while star N is white, its spectrum peaks at w =
3.6 x 1015s-1. Assuming that both stars radiate as black body, what is the
at w =
ratio of their radii?
Chapter 44 Solutions
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