Apparent Magnitude and Intensity Formula

In summary, the formula for Ia/Ib is 2.512^(Mb-Ma), where Ia and Ib are intensities of star a and star b and Mb and Ma are the apparent magnitudes of star A and star B. This is because magnitude is an inverse scale and there is a missing minus sign in the original formulas. The relative intensity of magnitude 5 is actually 0.01 relative to magnitude 0, with a ratio of 100 for a difference of 5.
  • #1
thegirl
41
1
Hey,
Could anyone explain why Ia/Ib=2.512^(Mb-Ma), Where "Ia" and "Ib" are intensities of star a and star b and "Mb" and "Ma" are the apparent magnitudes of star A and star B?

I thought the formula would be Ia/Ib=(2.512)^(Ma-Mb) because Ia=2.512^Ma and Ib=2.512^Mb.

Thank You
 
Astronomy news on Phys.org
  • #2
Magnitude is an "inverse" scale in this sense : magnitude 0 is very bright (about the brightest visible stars), magnitude 10 is very faint (invisible naked eye). There's a minus sign missing in your formulas for la, lb.
 
Last edited:
  • #3
Thank you so much! So the actual relative intensity of magnitude 5 is 0.1 relative to the apparent magnitude 0?

Thanks again!
 
  • #5
Thank You!
 

Related to Apparent Magnitude and Intensity Formula

1. What is apparent magnitude?

Apparent magnitude is a measure of the brightness of a celestial object as seen from Earth. It is expressed on a logarithmic scale, with lower numbers representing brighter objects and higher numbers representing dimmer objects.

2. How is apparent magnitude different from absolute magnitude?

Apparent magnitude is a measure of the brightness of a celestial object as seen from Earth, while absolute magnitude is a measure of the intrinsic brightness of the object. Absolute magnitude takes into account the distance of the object from Earth, while apparent magnitude does not.

3. What is the formula for calculating apparent magnitude?

The formula for calculating apparent magnitude is m = -2.5log(I/I0), where m is the apparent magnitude, I is the intensity of the object, and I0 is the intensity of a standard reference object with a magnitude of 0.

4. How does the intensity of an object affect its apparent magnitude?

The intensity of an object directly affects its apparent magnitude. As the intensity of an object increases, its magnitude becomes lower (brighter), and as the intensity decreases, its magnitude becomes higher (dimmer).

5. How is apparent magnitude used in astronomy?

Apparent magnitude is used in astronomy as a way to quantify the brightness of celestial objects. It is also used to classify stars by their brightness levels and to track changes in the brightness of variable stars. It is an important tool for studying and understanding the properties of objects in the universe.

Similar threads

I Are Intensity and Magnitude independent of the radius of a star?
    • Astronomy and Astrophysics
Replies
8
Views
2K
B What is the best source for this star data? (M44 Beehive Cluster)
    • Astronomy and Astrophysics
Replies
11
Views
1K
B Simple Derivation Of Euler's Formula And Applications
    • Calculus
Replies
2
Views
1K
Transforming FERMI SMARTS data from magnitude to flux
    • Astronomy and Astrophysics
Replies
1
Views
1K
I How would one convert measured magnitudes of a satellite object to radiant intensity?
    • Astronomy and Astrophysics
Replies
0
Views
339
Pulsating variable star mathematics question
    • Astronomy and Astrophysics
Replies
1
Views
2K
I What is the New White Dwarf Mass Limit?
    • Astronomy and Astrophysics
Replies
9
Views
2K
Force exerted on block B by Block A when being pushed on a frictionless surface
    • Introductory Physics Homework Help
Replies
3
Views
566
I Help with the color of a star cluster
    • Astronomy and Astrophysics
Replies
1
Views
2K
Need to derive a formula for the number of red giants
    • Introductory Physics Homework Help
Replies
8
Views
369

Hot Threads

Recent Insights

Back
Top