# Help with a simple exercise in astrophysics.

• Xalkias
In summary, the student is trying to solve an astrophysics problem but is having trouble. He is unsure of what equations to use and does not know what to do next.

#### Xalkias

<Moderator's note: Moved from a technical forum and thus no template.>

So i began studying on my own for my astrophycis class that will start on 2 weeks and i have trouble solving an exercise. So the exercise goes as follows: given that mbol=-2.5log(∫fλdλ)+Cbol and mbol=-26.83 for sun. Show that Cbol=-18.99 . I'm stuck and i can't find any hint from the book that I am studying.

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first of all, I think you should post your question as a homework problem here.
secondly, before we are allowed to help you, you should show some effort on your side, maybe an attempt to solve the problem, so we can see where exactly is the blocking point.
Which part is not clear to you? What equations related to the apparent magnitude are available to you?

I'm sorry I'm new to this forum.
Ok so In my mind I have to find f and then solve for C. So for the sun : ∫fdλ= L/4πd^2 (d=1AU) but then L is unknown so I can't calculate F. Temperature is not given so I can't use that either to calculate F. What should I do

Xalkias said:
I'm sorry I'm new to this forum.
Ok so I know for the sun : ∫fdλ= L/4πd^2 (d=1AU) but then L is unknown so I can't calculate F. Temperature is not given so I can't use that either to calculate F.

Great, you actually know the solution :) I think in many astrophysics problems like this one, you won't be given Solar luminosity or irradiance each time in the problem definition. I am pretty sure you can find at least one of these values in your book. Can you?

Ohh Yes there is a lists of all luminosities in the book but I thought they would mention if this lists was needed.