Universe: Stars And Galaxies
6th Edition
ISBN: 9781319115098
Author: Roger Freedman, Robert Geller, William J. Kaufmann
Publisher: W. H. Freeman
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Chapter 20, Problem 53Q
To determine
Theratio of the maximum luminosity of
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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
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 /
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
Consider 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 km
Chapter 20 Solutions
Universe: Stars And Galaxies
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- A Type Ia supernova is observed and achieves an apparent magnitude of m = 19.89 at peak brightness. The absolute magnitudes of Type Ia supernovae at peak brightness are known to be M=−19. Determine the distance to the supernovae in units of Mpc.arrow_forwardAs we have discussed, Sirius B in the Sirius binary system is a white dwarf with MB ∼ 1M , LB ∼ 0.024L ,and rB ∼ 0.0084r . For such a white dwarf, the temperature at the center is estimated to be ∼ 107 K.If Sirius B’s luminosity were due to hydrogen fusion, what is the upper limit of the mass fraction of thehydrogen in such a white dwarf?Step 1: Calculate the observed energy production rate per unit mass (remember luminosity is energy outputper unit time).Step 2: Use the per unit mass energy generation rate of hydrogen fusion (via PP chain) to estimate thepossible hydrogen mass fraction given the condition at the center of the white dwarf.arrow_forwardThe star HD 93250 in the Carina Nebula is a bright O-type star. It has a reported apparent magnitude in the V band of mV = 7.41 and V band absolute magnitude of MV = −6.14. Using these values calculate the distance to HD 93250 in parsec. The distance to HD 93250 has been measured by other means as 2350 pc. Compare your calculated value of the distance with the measured value, and give a possible explanation for any difference. Calculate the value of the interstellar extinction in the V band AV that would account for the difference in the distances. The parameter E(B − V ) = AB − AV , where AB and AV are the extinctions in the B and V bands, is often used to characterize interstellar extinction. For the star HD 93250 the value E(B − V ) = 0.48 has been measured. Given the above value of E(B − V ) for HD 93250, calculate the extinction in the B band, and explain why the parameter E(B − V ) is often called the “reddening.” The B band apparent magnitude of HD 93250 is mB = 8.12. Calculate…arrow_forward
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