Stellar Temperature Calculator Formula

Understand the math behind the stellar temperature calculator. Each variable explained with a worked example.

Use the Stellar Temperature Calculator

Formulas Used

Effective Temperature

temperature = 4600 * (1 / (0.92 * bv_index + 1.7) + 1 / (0.92 * bv_index + 0.62))

Variables

VariableDescriptionDefault
bv_indexB-V Colour Index0.65

How It Works

Stellar Temperature from Colour

The B-V colour index measures the difference in brightness between blue (B) and visual (V) filters. Bluer (hotter) stars have lower B-V.

Ballesteros Formula

T = 4600 × (1/(0.92(B-V)+1.7) + 1/(0.92(B-V)+0.62)) K

The Sun has B-V ≈ 0.65, giving T ≈ 5780 K.

Worked Example

The Sun: B-V = 0.65.

bv_index = 0.65
  1. 010.92 × 0.65 = 0.598
  2. 021/(0.598+1.7) + 1/(0.598+0.62) = 1/2.298 + 1/1.218
  3. 03= 0.4352 + 0.8210 = 1.2562
  4. 04T = 4600 × 1.2562 ≈ 5778 K

Ready to run the numbers?

Open Stellar Temperature Calculator