Stellar Flux Calculator Formula
Understand the math behind the stellar flux calculator. Each variable explained with a worked example.
Formulas Used
Observed Flux
flux = luminosity / (4 * pi * pow(distance, 2))Variables
| Variable | Description | Default |
|---|---|---|
luminosity | Luminosity(W) | 3.828e+26 |
distance | Distance(m) | 149600000000 |
How It Works
Stellar Flux
Flux is the power received per unit area at a given distance from a luminous source.
Inverse-Square Law
F = L / (4π d²)
As distance doubles, flux drops to one-quarter.
Worked Example
Solar flux at 1 AU.
luminosity = 3.828e+26distance = 149600000000
- 01F = L / (4π d²)
- 024π d² = 4π × (1.496e11)² = 2.812e23
- 03F = 3.828e26 / 2.812e23 ≈ 1361 W/m²
Frequently Asked Questions
What is the solar constant?
About 1361 W/m², the flux from the Sun at 1 AU. It varies slightly with solar activity.
How does flux relate to apparent magnitude?
Magnitude is a logarithmic scale of flux. A difference of 5 magnitudes corresponds to a factor of 100 in flux.
Is flux the same as irradiance?
In astronomy, flux and irradiance are often used interchangeably for power per unit area received from a distant source.
Ready to run the numbers?
Open Stellar Flux Calculator