UNIVERSE (LOOSELEAF):STARS+GALAXIES
6th Edition
ISBN: 9781319115043
Author: Freedman
Publisher: MAC HIGHER
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Chapter 20, Problem 62Q
To determine
(a)
The height of the outburst of Betelgeuse and its brightness as a fraction of brightness of Sun after a Type II supernova.
To determine
(b)
The brightness the Type II supernova Betelgeuse when compared with that of Venus (
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International Astronomical Union reported on 24 Feb 1987:
An object was discovered on Feb. 24.37 UT (position R.A. = 5h35m.8, Decl. = -69
18'), obtained m = 4.8 on Feb. 24.454 UT. This object proved to be the most famous
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It is classified as a SN of the type Il in the Large Magellanic Cloud (SN1987A). Its
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Ebefore
An object was discovered on Feb. 24.37 UT (position R.A. = 5h35m.8, Decl. = -69
18'), obtained m = 4.8 on Feb. 24.454 UT. This object proved to be the most famous
supernova (SN) in the 20th Century and the brightest visible from Earth since 1604.
It is classified as a SN of the type Il in the Large Magellanic Cloud (SN1987A). Its
brightness peaked in May 1987, with an apparent magnitude of m = 2.8.
a) Find the absolute magnitude M of the SN1987A at maximum. Distance of the
LMC is 51,400 pc.
b) The progenitor (before SN explosion) star was a blue supergiant of the
apparent magnitude m = 12.8. How much brighter (in terms of flux density)
this SN was at maximum compared to the progenitor star. Find the ratio FSN/
Ebetore
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 20 Solutions
UNIVERSE (LOOSELEAF):STARS+GALAXIES
Ch. 20 - Prob. 1QCh. 20 - Prob. 2QCh. 20 - Prob. 3QCh. 20 - Prob. 4QCh. 20 - Prob. 5QCh. 20 - Prob. 6QCh. 20 - Prob. 7QCh. 20 - Prob. 8QCh. 20 - Prob. 9QCh. 20 - Prob. 10Q
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- 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) 36.854 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.arrow_forwardConsider a star with more brightness at 280 pc from the Sun. Suppose this star gets exploded as a supernova at a temperature of 18000 K. The absolute bolometric magnitude of this supernova is-12.24. Calculate its diameter by assuming a sphere at maximum light. (Assume the luminosity of Sun as 3.8×1026 W, the mass of thesun as 1.9 ×1030 kg, and surface temperature of Sun as 5778 K).(a) 1.7×108 km(6) 3.5x108 km(c) 5.2x108 km(d) 6.9 x108 kmarrow_forwardA Type la supernova is observed and achieves an apparent magnitude of m = 19.89 at peak brightness. The absolute magnitudes of Type la supernovae at peak brightness are known to be M = –19. Determine the distance to the supernovae in units of Мрс. Select one: а. 600 O b. 1000 О с 10 O d. 200 е. 300arrow_forward
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