Calculating Distance to Cefeide Star w/ Stellar Extinction

[Sux]

Hi! In this problem I have to calculate the distance to a cefeide star, I know visual magnitude, m_{v}, his magnitude in B range, m_{b} and its period, P.

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

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

Where A{v} is visual magnitude extinction.

As I know color index:

m_{b}-m_{v}=M_{B}-M_{V}+E_{B-V}

Where: E_{B-V} is color excess.

And:

\frac{A_{V}}{E_{B-V}}\approx3I just need to calculate absolute magnitude in B range, M_{B}, 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.

 

[negitron]

Your English is quite good, although I don't understand what you mean by "extinction" (it means something specific in English--it's what happened to the dinosaurs). If you define it clearly, I can probably give you the correct word.

 

[captn]

Stellar extinction has to do with the loss of light due to gas/dust in the path to the observer --atmospheric extinction due to volcanic dust, extinction due to dust around a star, for example.

It must be corrected for to determine the intrinsic brightness of a star.

Neil

 

[Sux]

Yes, stellar "extinction" is the loss of flux or brightness due to interstellar dust.

Here you have it: http://nedwww.ipac.caltech.edu/level5/Mathis/Mathis1.html"

Thanks for the answers.