HINT:#
The question asks us to determine the total energy emitted by Cen X-3.
HINT:#
In 3C273 Activity 3, we learned that Chandra observes 10-11 ergs/count*s of energy over the area of one square centimeter. From our light curve of Cen X-3, we can see that Chandra detects roughly 75 counts/s when pointed directly towards it. The problem tells us that the distance from Cen X-3 to the earth is approximately 3 x 1022 cm.
HINT:#
ET = Ecm2 * 4Πd2
HINT:#
Ecm2 = 10-11 ergs/count * 75 counts/s*cm2 = 7.5 x 10-10 ergs/s*cm2
d = 3 x 1022 cm
HINT:#
Let's use unit analysis:
ET(ergs/s) = Ecm2(ergs/s*cm2) * 4Πd2(cm2)
All units cancel except for ergs/s, so we do not need to convert any units!
HINT:#
ET = Ecm2 * 4Πd2
= 7.5 x 10-10 ergs/s * cm 2 * 4Π (3 x 1022 cm)2
= 8.5 x 1036 ergs/s

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