Proxima Centauri vs Rigil Kentaurus
These two belong to the same stellar system, the nearest to the Sun, and yet nothing about their appearance matches. Rigil Kentaurus is the G-type star at 4.32 light-years and magnitude −0.01, among the brightest points in the sky. Proxima Centauri is the M-type red dwarf at 4.23 light-years and magnitude 11.01, well beyond naked-eye reach and requiring a telescope. Eleven magnitudes separate them, a ratio of some 25,000 in light, and because their distances are nearly identical the same ratio holds intrinsically — absolute magnitudes of +4.38 and +15.45. Proxima is fractionally the closer of the two, and by that margin the closest known star to the Sun.
Property comparison
| Property | Proxima Centauri | Rigil Kentaurus |
|---|---|---|
| Designation | N/A | Alp1Cen |
| Constellation | Centaurus | Centaurus |
| Spectral Class | Class M — M-type (Red) | Class G — G-type (Yellow) |
| Apparent Magnitude | +11.01 | -0.01 |
| Absolute Magnitude | 15.45 | 4.38 |
| Distance | 4.2 ly | 4.3 ly |
| Mass | N/A | N/A |
| Radius | N/A | N/A |
| Temperature | N/A | N/A |
| Luminosity | N/A | N/A |
Full data for each star: Proxima Centauri · Rigil Kentaurus
Key differences
Key Differences
- ◆ Both are members of the Alpha Centauri system, the nearest stellar system to the Sun.
- ◆ Rigil Kentaurus (Alpha Cen A) is a G-type solar analog; Proxima Centauri is an M-type red dwarf.
- ◆ Rigil Kentaurus is slightly more massive and luminous than the Sun; Proxima Centauri has just 12% of the Sun's mass.
- ◆ Proxima Centauri orbits the Alpha Centauri AB pair at a vast distance of roughly 0.2 light-years.
- ◆ Rigil Kentaurus is visible to the naked eye at magnitude −0.01; Proxima is invisible without a telescope.
When to Observe
Proxima Centauri
Rigil Kentaurus culminates at midnight at the end of April. At declination −60° it is a southern object, circumpolar from Australia, New Zealand, southern Africa and southern South America, and never rising north of about 30°N.
Rigil Kentaurus
Proxima Centauri shares the same window and the same restriction at declination −62°, but its magnitude of 11.01 puts it beyond binoculars; a telescope of moderate aperture and a good finder chart are needed to isolate it from the background field.