Luminosity of Sirius A
| Value | 9.72e27 W |
| Status | Measured: ± 5.00e+26 W (0.051 relative) |
| Source | Liebert et al. (2005), 25.4 ± 1.3 L⊙ |
| Categories | Astronomicalstellar |
| nanowatt | 9.7200000e+36 nW |
| erg per second | 9.7200000e+34 erg/s |
| microwatt | 9.7200000e+33 μW |
| milliwatt | 9.7200000e+30 mW |
| foot pound-force per minute | 4.3014625e+29 ft·lbf/min |
| BTU per hour | 3.3166017e+28 BTU/h |
| watt | 9.7200000e+27 W |
| kilocalorie per hour | 8.3576956e+27 kcal/h |
| foot pound-force per second | 7.1691041e+27 ft·lbf/s |
| thousand BTU per hour | 3.3166017e+25 MBH |
| metric horsepower | 1.3215522e+25 PS |
| horsepower (mechanical) | 1.3034735e+25 hp |
| electrical horsepower | 1.3029491e+25 hp (elec) |
| kilowatt | 9.7200000e+24 kW |
| ton of refrigeration | 2.7638347e+24 ton |
| boiler horsepower | 9.9087619e+23 bhp |
| million BTU per hour | 3.3166017e+22 MMBTU/h |
| megawatt | 9.7200000e+21 MW |
| gigawatt | 9.7200000e+18 GW |
| terawatt | 9.7200000e+15 TW |
| solar luminosity | 25.39185 Lsun |
Learning zone
Sirius A radiates 25 Suns' worth of power from only 1.7 times the Sun's diameter, because luminosity is merciless about temperature: at 9940 K against the Sun's 5772, the Stefan–Boltzmann T⁴ law multiplies every square metre of its surface ninefold. The same temperature shifts its peak emission into the ultraviolet — the eye-visible brilliance of Sirius undersells it, and its bolometric correction is a standard classroom exercise in the difference between visual and total luminosity.
Champions of precision photometry, astronomers have measured this star's flux for a century and a half — Sirius was among the first stars whose energy output was compared directly against laboratory standards, and it remains a calibration source for infrared astronomy today. Through the inverse-square law, the luminosity and the 8.6-light-year distance reproduce exactly the −1.46 apparent magnitude that has made Sirius the reference point of brightness scales since Hipparchus ranked it first.