Luminosity of Alpha Centauri A
| Value | 5.815e26 W |
| Status | Measured: ± 7.00e+24 W (0.012 relative) |
| Source | Kervella et al. (2017), 1.519 ± 0.018 L⊙ |
| Categories | Astronomicalstellar |
| nanowatt | 5.8150000e+35 nW |
| erg per second | 5.8150000e+33 erg/s |
| microwatt | 5.8150000e+32 μW |
| milliwatt | 5.8150000e+29 mW |
| foot pound-force per minute | 2.5733543e+28 ft·lbf/min |
| BTU per hour | 1.9841604e+27 BTU/h |
| watt | 5.8150000e+26 W |
| kilocalorie per hour | 5.0000000e+26 kcal/h |
| foot pound-force per second | 4.2889239e+26 ft·lbf/s |
| thousand BTU per hour | 1.9841604e+24 MBH |
| metric horsepower | 7.9061997e+23 PS |
| horsepower (mechanical) | 7.7980435e+23 hp |
| electrical horsepower | 7.7949062e+23 hp (elec) |
| kilowatt | 5.8150000e+23 kW |
| ton of refrigeration | 1.6534670e+23 ton |
| boiler horsepower | 5.9279270e+22 bhp |
| million BTU per hour | 1.9841604e+21 MMBTU/h |
| megawatt | 5.8150000e+20 MW |
| gigawatt | 5.8150000e+17 GW |
| terawatt | 581,500,000,000,000 TW |
| solar luminosity | 1.51907 Lsun |
Learning zone
Alpha Centauri A outshines the Sun by half again, and the excess is a clock. Main-sequence stars brighten slowly as helium ash accumulates in their cores, so a star of essentially solar mass and composition running 52 per cent over solar luminosity must be older — age estimates from this and from asteroseismology put the system near six billion years, about 1.5 billion ahead of the Sun. Looking at Alpha Cen A is the closest astronomy comes to a photograph of our own star's middle age.
The luminosity is among the most secure for any star because every input is nearby and measurable: apparent brightness, a parallax good to a tenth of a per cent, and an interferometric radius. Combined through the inverse-square law it also sets the system's habitable zone — spanning roughly 1.2 au around A, a region dynamically stable despite companion B, which is why proposed planet-hunting missions from space coronagraphs to Breakthrough initiatives keep this system first on the target list.