Find the temperature and total radiancy of star

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Homework Help Overview

The discussion revolves around determining the temperature and total radiancy of two stars, A and B, based on their properties as blackbodies and the application of Wien's law. The original poster presents a scenario involving relative velocities and Doppler shifts as well.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to apply Wien's formula to relate the temperatures of the two stars and raises a question regarding the Doppler effect in relation to their relative velocities.

Discussion Status

Some participants inquire about the original poster's prior efforts on the problems, indicating a focus on understanding the work done before seeking assistance. There is an emphasis on the forum's guidelines regarding showing effort in problem-solving.

Contextual Notes

The original poster's mention of specific temperatures and wavelengths suggests a need for clarity on the assumptions made regarding the stars' properties and the implications of their relative motion.

stunner5000pt
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Thank you in advance for your help!

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 and total radiancy 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 between 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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What have you done so far on any of these problems?
 
stunner5000pt said:
what do you mean ?

By the way I'm fine i understand this problem quite well, i would appreciate your help with this one

https://www.physicsforums.com/showthread.php?t=49868

What I mean is that according to the forum rules you should indicate what work you've done so far on the problems for which you are seeking help. People are more than willing to help out if you give some indication of the effort you've made at solving a problem before you post it here but they reluctant to provide outright solutions when problems are posted with no work shown. It's not a homework service!
 

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