Mass of Proxima Centauri
| Value | 2.428e29 kg |
| Status | Measured: ± 4.00e+27 kg (0.016 relative) |
| Source | Mann et al. (2015) mass–luminosity calibration, 0.1221 ± 0.0022 M⊙, as adopted by Suárez Mascareño et al. (2020) |
| Categories | Astronomicalstellar |
| unified atomic mass unit (dalton) | 1.4621758e+56 u |
| picogram | 2.4280000e+44 pg |
| nanogram | 2.4280000e+41 ng |
| microgram | 2.4280000e+38 μg |
| milligram | 2.4280000e+35 mg |
| centigram | 2.4280000e+34 cg |
| grain | 3.7469766e+33 gr |
| metric carat | 1.2140000e+33 ct |
| gram | 2.4280000e+32 g |
| pennyweight | 1.5612403e+32 dwt |
| dram | 1.3703229e+32 dr |
| ounce | 8.5645180e+30 oz |
| troy ounce | 7.8062013e+30 oz t |
| troy pound | 6.5051677e+29 lb t |
| pound | 5.3528237e+29 lb |
| kilogram | 2.4280000e+29 kg |
| stone | 3.8234455e+28 st |
| slug | 1.6637085e+28 slug |
| US hundredweight | 5.3528237e+27 cwt |
| UK long hundredweight | 4.7793069e+27 cwt (UK) |
| quintal | 2.4280000e+27 q |
| US short ton | 2.6764119e+26 ton |
| metric tonne | 2.4280000e+26 t |
| UK long ton | 2.3896534e+26 long ton |
| kilotonne | 2.4280000e+23 kt |
| megatonne | 2.4280000e+20 Mt |
| gigatonne | 2.4280000e+17 Gt |
| Earth mass | 40,655.035 Mearth |
| solar mass | 0.12210761 Msun |
Learning zone
Proxima sits close to the bottom of the main sequence: at 0.122 solar masses it is only half again the minimum mass for sustained hydrogen fusion, below which objects are brown dwarfs. Small stars are the universe's misers — fully convective, so the entire star cycles through the core as fuel, burned at a trickle. Proxima's expected main-sequence lifetime is measured in trillions of years, hundreds of times the current age of the universe; every red dwarf ever formed is still in its infancy.
The mass is what the solver needs for Proxima b, the temperate planet found in 2016 by the radial-velocity wobble it raises in this star — an 11.2-day orbit at 0.049 au whose period, radius and velocity all follow from M via Kepler. The frugal energy budget comes with a temper: Proxima is a flare star, and a 2019 superflare briefly doubled its ultraviolet output, the central caveat over its planet's habitability.