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Hello I'm Tim. I'm a professional software engineer, web developer, designer, photographer and astronomer from the UK.

I started blogging in 2001 as a way to record my activities and hobbies. I find blogging allows me to reflect on what I've been doing in life and what I've learned from it. It's a great tool for self-growth, and I recommend it to anyone.

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is absolute magnitude or apparent magnitude relative to the distance from Earth?

Why does the size of a star correlate with bolometric luminosity? why cant a star be relatively small but bolometrically bright, or large but bolometrically dim?

Does anybody know how to "unaccount" for the atmosphere when measuring absolute magnitude?

okay so what is the difference between absolute and apparent magnitude?

Apparent Magnitude - is how bright something appears to you from were you are.

Absolute Magnitude - is how bright something looks from a set distance of 10 parsecs (32.6 lightyears).

A dim star will still be very bright if you are really close to it. Conversely, a really bright star can be seen from very far away.

I am very interested in astronomy, but I suck at mathematic calculations (go figure...). I am taking a class currently, and a question posed is as follows:

Polaris is a second-magnitude star. Phi Pegasi is about sixteen times fainter than Polaris. What is the approximate magnitude of Phi Pegasi?

I have been given the choices of 18, -14, 3, -3, and 5. I do not know the calculation/equation that I need to use to reach an answer. I am not asking that you answer this for me, but I would like to know / to understand the appropriate equation. Please respond via e-mail, as soon as possible. Thank you!

The answer is 5th magnitude (apparent).

each magnitude is 2.512 brighter or fainter then the next increment. So a 1st magnitude star is 2.512 times brighter then a 2nd magnitude star. Therefore, 2.512 * 2.512 * 2.512 = 15.85 times brighter or fainter - notice that 15.85 is close to 16). So that means there are 3 magnitudes of difference between Polaris and Phi Pegasi - so 2 (mag of Polaris) + 3 (mag diff) = 5 th mag for Phi Pegasi.

Does anybody know the equation relating all-spectrum flux with bolometric apparent magnitude?

If we know that a certain star has a bolometric apparent magnitude of EXACTLY zero, then how many watts per meter squared do you get from it when you integrate over the entire spectrum?

omg this calculation is so difficult

(m-M) = 5logd-5. Great but how do I get d = ?????

I cannot see how to rearrange can you help

Many thanks

d = 10^(1 + (m-M)/5)

10 raised to the power of 1 plus the quantity of apparent mag minus absolute mag divided by 5.

a quick sanity check: if m = M then 10 raised to the 1st power is 10. which is 10 parsecs.