# What is the intrinsic colour of the star? [closed]

Hey I have this question and I am wrestling with it all day and I am completely lost.

The V magnitude of a star is 15.1, B-V =1.6, and absolute magnitude Mv= 1.3 The extinction in the direction of the star in the visual band is av = 1 mag/kpc. What is the intrinsic colour?

Can somebody help me?

Edit: Ok, apparently I have to calculate first the distance and after that the excess colour and then I can calculate the intristic colour.

I guess I need this formula for the distance: V = Mv + 5log(r/10pc) + Av But if i fill this in and get the R I get a different r and I dont know what the next step if to go to the excess colour.

## closed as off-topic by Kyle Kanos, Waffle's Crazy Peanut, John Rennie, Qmechanic♦Jan 9 '14 at 15:06

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• What didn't you understand here? – Torsten Hĕrculĕ Cärlemän Jan 9 '14 at 12:06
• How I can go from these values tot the intrinstic colour. I have no idea what formulas I need to use – user1200276 Jan 9 '14 at 12:51