Hi! In this problem I have to calculate the distance to a cefeide star, I know visual magnitude, [tex]m_{v}[/tex], his magnitude in B range, [tex]m_{b}[/tex] and its period, [tex]P[/tex].(adsbygoogle = window.adsbygoogle || []).push({});

Well, if I ignore extinction, I can calculate the distance with [tex]M_{V}[/tex]:

[tex]m_{v}=M_{V}+5log(\frac{r}{10})+A_{v}[/tex]

Where [tex]A{v}[/tex] is visual magnitude extinction.

As I know color index:

[tex]m_{b}-m_{v}=M_{B}-M_{V}+E_{B-V}[/tex]

Where: [tex]E_{B-V}[/tex] is color excess.

And:

[tex]\frac{A_{V}}{E_{B-V}}\approx3[/tex]

I just need to calculate absolute magnitude in B range, [tex]M_{B}[/tex], to calculate extinction and be able to calculate the distance.

Any ideas about how could I do it?

I apologize for my mistakes, I am still learning English.

Thanks.

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# Stellar extinction

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