Understanding Our Universe
3rd Edition
ISBN: 9780393614428
Author: PALEN, Stacy, Kay, Laura, Blumenthal, George (george Ray)
Publisher: W.w. Norton & Company,
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Chapter 12, Problem 37QAP
(a)
To determine
The luminosity of a star; compare it with given values in Table 12.1.
(b)
To determine
The luminosity of a star; compare it with given values in Table 12.1.
(c)
To determine
The luminosity of a star; compare it with given values in Table 12.1.
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Finally estimate the lifetime of an M0 spectral type star if the total mass of the star is M = 0.51M⊙ , and it has a total luminosity L = 7.7× 10−2L⊙. Make the same assumptions as the previous two problems. How does your calculated Main Sequence lifetime for the M0 type star compare to the Main Sequence lifetime you calculated for the Sun?
A star with spectral type A0 has a surface temperature of 9600 K and a radius of 2.2 RSun. How many times more luminous is this star than the Sun? (if it is less luminous enter a number less than one)
This star has a mass of 3.3 MSun. Using the simple approximation that we made in class, what is the main sequence lifetime of this star? You may assume that the lifetime of the sun is 1010 yr.
Compare this to the lifetime of a A0 star listed in Table 22.1 (computed using a more sophisticated approach). Is the value you calculated in the previous problem longer or shorter than what is reported in the table? (L for longer, S for shorter) (You only get one try at this problem.)
A main sequence star of mass 25 M⊙has a luminosity of approximately 80,000 L⊙. a. At what rate DOES MASS VANISH as H is fused to He in the star’s core? Note: When we say “mass vanish '' what we really mean is “gets converted into energy and leaves the star as light”. Note: approximate answer: 3.55 E14 kg/s b. At what rate is H converted into He? To do this you need to take into account that for every kg of hydrogen burned, only 0.7% gets converted into energy while the rest turns into helium. Approximate answer = 5E16 kg/s c. Assuming that only the 10% of the star’s mass in the central regions will get hot enough for fusion, calculate the main sequence lifetime of the star. Put your answer in years, and compare it to the lifetime of the Sun. It should be much, much shorter. Approximate answer: 30 million years.
Chapter 12 Solutions
Understanding Our Universe
Ch. 12.1 - Prob. 12.1CYUCh. 12.2 - Prob. 12.2CYUCh. 12.3 - Prob. 12.3CYUCh. 12.4 - Prob. 12.4CYUCh. 12.5 - Prob. 12.5CYUCh. 12.6 - Prob. 12.6CYUCh. 12 - Prob. 1QAPCh. 12 - Prob. 2QAPCh. 12 - Prob. 3QAPCh. 12 - Prob. 4QAP
Ch. 12 - Prob. 5QAPCh. 12 - Prob. 6QAPCh. 12 - Prob. 7QAPCh. 12 - Prob. 8QAPCh. 12 - Prob. 9QAPCh. 12 - Prob. 10QAPCh. 12 - Prob. 11QAPCh. 12 - Prob. 12QAPCh. 12 - Prob. 13QAPCh. 12 - Prob. 14QAPCh. 12 - Prob. 15QAPCh. 12 - Prob. 16QAPCh. 12 - Prob. 17QAPCh. 12 - Prob. 18QAPCh. 12 - Prob. 19QAPCh. 12 - Prob. 20QAPCh. 12 - Prob. 21QAPCh. 12 - Prob. 22QAPCh. 12 - Prob. 23QAPCh. 12 - Prob. 24QAPCh. 12 - Prob. 25QAPCh. 12 - Prob. 26QAPCh. 12 - Prob. 27QAPCh. 12 - Prob. 28QAPCh. 12 - Prob. 29QAPCh. 12 - Prob. 30QAPCh. 12 - Prob. 32QAPCh. 12 - Prob. 33QAPCh. 12 - Prob. 34QAPCh. 12 - Prob. 35QAPCh. 12 - Prob. 36QAPCh. 12 - Prob. 37QAPCh. 12 - Prob. 38QAPCh. 12 - Prob. 39QAPCh. 12 - Prob. 40QAPCh. 12 - Prob. 42QAPCh. 12 - Prob. 43QAPCh. 12 - Prob. 44QAPCh. 12 - Prob. 45QAP
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