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Stars act like perfect blackbodies. Star A has a surface temperature of 10^12 K. For another star B the wavelength at which the spectral radiancy is a maximum [tex] (\lambda_{max})^B [/tex] is half taht of star A.

a) Find the temperature andtotalradiancy of star B.(per sq m)

Using Wien's formula

Lambda T = constant

Lambda(A) T(A) = 2 Lambda (B) T(A) = Lambda(B) = T(B)

So the temperature of B is twice that of A

Also since w = 2898micormetres K then i can find out lambda.

C) A spaceship is positioned on the straight line betwen the stars A and B. The spaceship is at rest with respect to star A. Stars A and B have relative velocities such that the spectral radiancy from B appears to be 1/3 rd its wavelength. What is the relative velocity of th stars?

If the wavelength is smaller than B must be approching A(yes?) then the doppler shift formula iwth the + on top would be used.

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# Homework Help: Find the temperature and total radiancy of star

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