# Calculating absolute magnitude and apparent magnitude

• dalai_lala
In summary, the conversation discusses finding the absolute magnitude of Proxima Centauri using the formula m-M = 5 log10(d/10 pc), where d = 1/p". The person is unsure of how to obtain the apparent magnitude, but it is given in the problem as 11.1. They proceed to solve for the absolute magnitude using the given values.
dalai_lala
Ummm... never mind, we found it...

## Homework Statement

Given Proxima Centauri with parallax angle of 0.769" and apparent bolometric magnitude of 11.1... what is its absolute magnitude?

## Homework Equations

I get that I should use m-M = 5 log10(d/10 pc) and I understand that d = 1/p".

What I really need to know is: what do I use to get apparent magnitude? After I get m I can plug and chug, and I'm fine with that... but how do I get m?

Apparent magnitude was not given and I can't look it up for a quiz or test.

## The Attempt at a Solution

so far...

m-M = 5 log10 [(1/0.769)/10]

or M = m - 5 log10 (.1300)

But I'm still stuck on where to go for m...

Thanks!

Lori the Totally Lost English Major

Last edited:
They gave you the "apparent bolometric magnitude", just use that. The only difference between that and "apparent visual magnitude" is what wavelengths of light are being measured.

## 1. What is the difference between absolute magnitude and apparent magnitude?

Absolute magnitude is a measure of the intrinsic brightness of a celestial object, while apparent magnitude is a measure of its perceived brightness from Earth. Absolute magnitude takes into account the distance of the object, while apparent magnitude does not.

## 2. How is absolute magnitude calculated?

Absolute magnitude is calculated by measuring the object's apparent magnitude and correcting for its distance based on the inverse square law of light. The formula is: Absolute Magnitude = Apparent Magnitude - 5(log(d) - 1), where d is the distance in parsecs.

## 3. What is the reference point for absolute magnitude?

The reference point for absolute magnitude is the brightness of a star as seen from a distance of 10 parsecs. This is known as the standard absolute magnitude, with a value of 0.

## 4. How is apparent magnitude measured?

Apparent magnitude is measured using a system of numbers, with smaller numbers indicating brighter objects and larger numbers indicating dimmer objects. The brightest objects in the sky have negative apparent magnitudes, while the dimmest objects have magnitudes around 30.

## 5. Why is it important to calculate both absolute and apparent magnitude?

Calculating both absolute and apparent magnitude allows us to understand the true brightness of celestial objects and their distances from Earth. This information is essential in studying the properties and evolution of stars and other objects in the universe.

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