You can know the temperature of a star by fitting a black body spectrum. BUt what if the star is moving with some radial velocity v? I worked out that:(adsbygoogle = window.adsbygoogle || []).push({});

[tex]I(\lambda_0,T)=\frac{8\pi h c}{\lambda_0^5}\frac{1}{e^{\frac{hc}{\lambda_0kT}}-1}[/tex]

[tex]\lambda=\lambda_0\sqrt{\frac{1+\frac{v}{c}}{1-\frac{v}{c}}}[/tex]

[tex]I(\lambda,T)=I(\lambda_0,T)\frac{d\lambda_0}{d\lambda}[/tex]

[tex]I(\lambda,T)=\frac{8\pi h c}{\lambda^5}\frac{1}{e^{\frac{hc}{\lambda kT} \sqrt{\frac{1+\frac{v}{c}}{1-\frac{v}{c}}}}-1}[/tex]

[tex]=I(\lambda,T')[/tex]

where [tex]T'=T\sqrt{\frac{1-\frac{v}{c}}{1+\frac{v}{c}}}}[/tex]

Am I correct here? If so, how can we actually tell the temperature of stars?

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# Doppler shifted blackbody spectrum

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