The brightest star in the sky is Sirius, the Dog Star. Itis actually a binary system of two stars, the smaller one (Sirius B)being a white dwarf. Spectral analysis of Sirius B indicates that itssurface temperature is 24 000 K and that it radiates energy at a totalrate of 1.0 · 1025 W. Assume that it behaves like an ideal blackbody.(a) What is the radius of Sirius B? Express your answer in kilometersand as a fraction of our Sun’s radius (R= 6.96 · 108 m). (b) Whichstar radiates more total energy per second, the hot Sirius B or the(relatively) cool Sun with a surface temperature of T = 5800 K? Tofind out, calculate the ratio of the total power radiated by our Sun tothe power radiated by Sirius B.
The brightest star in the sky is Sirius, the Dog Star. It
is actually a binary system of two stars, the smaller one (Sirius B)
being a white dwarf. Spectral analysis of Sirius B indicates that its
surface temperature is 24 000 K and that it
rate of 1.0 · 1025 W. Assume that it behaves like an ideal blackbody.
(a) What is the radius of Sirius B? Express your answer in kilometers
and as a fraction of our Sun’s radius (R= 6.96 · 108 m). (b) Which
star radiates more total energy per second, the hot Sirius B or the
(relatively) cool Sun with a surface temperature of T = 5800 K? To
find out, calculate the ratio of the total power radiated by our Sun to
the power radiated by Sirius B.
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