B−V color index to peak wavelength
Type a value in B−V to get it in nm instantly.
869.4nm
Nothing on our list is smaller: Betelgeuse is 1.08× hotter. Its light peaks at about 869.4 nm.
What it means
How hot is that star?
Ballesteros (2012) blackbody fit, for B−V from −0.4 to 2.5; real stars deviate by a few percent, and dust reddening makes stars look cooler.
The math
How to convert B−V to nm
T = 4600 × (1 ÷ (0.92 BV + 1.7) + 1 ÷ (0.92 BV + 0.62)) K; peak wavelength = 2,897,772 nm·K ÷ T.
Example: 1.85 B−V = 869.367 nm.
Every unit
That star in every measure
Tables
B−V to nm conversion table
| B−V | nm |
|---|---|
| -0.3 B−V | 174.539 nm |
| -0.2 B−V | 213.311 nm |
| -0.1 B−V | 250.395 nm |
| 0 B−V | 286.193 nm |
| 0.2 B−V | 354.988 nm |
| 0.4 B−V | 421.173 nm |
| 0.6 B−V | 485.589 nm |
| 0.65 B−V | 501.481 nm |
| 0.8 B−V | 548.751 nm |
| 1 B−V | 610.991 nm |
| 1.2 B−V | 672.536 nm |
| 1.5 B−V | 763.877 nm |
| 1.85 B−V | 869.367 nm |
nm to B−V conversion table
| nm | B−V |
|---|---|
| 175 nm | -0.298841 B−V |
| 213 nm | -0.20082 B−V |
| 250 nm | -0.101084 B−V |
| 286 nm | -0.000547346 B−V |
| 355 nm | 0.200035 B−V |
| 421 nm | 0.399469 B−V |
| 486 nm | 0.601291 B−V |
| 501 nm | 0.648482 B−V |
| 549 nm | 0.800796 B−V |
| 611 nm | 1.00003 B−V |
| 673 nm | 1.20152 B−V |
| 764 nm | 1.50041 B−V |
| 869 nm | 1.84878 B−V |
Quick answers
Quick answers
- How many nm is 1 B−V?
- 1 B−V is 610.991 nm.
- How many nm is 1.85 B−V?
- 1.85 B−V is 869.367 nm.
The units
About these units
B−V color index (B−V)
Difference of blue and visual magnitudes.
Peak wavelength (nm)
Where its light is brightest (Wien’s law).
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