  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Octans |
| Right ascension | 21h 50m 54.56355s[1] |
| Declination | −82° 43′ 08.0450″[1] |
| Apparent magnitude (V) | 5.27[2] (5.64 + 7.25)[3] |
| Characteristics | |
| Spectral type | G8-K0III[4] + kA3hA7VmA8[5] |
| U−B color index | +0.47[6]/+2.20[5] |
| B−V color index | +0.75[6] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | −10.18±0.13[7] km/s |
| Proper motion (μ) | RA: +69.803[7] mas/yr Dec.: −33.013[7] mas/yr |
| Parallax (π) | 8.1897±0.0878 mas[7] |
| Distance | 398 ± 4 ly (122 ± 1 pc) |
| Absolute magnitude (MV) | +0.40[5] |
| B | |
| Proper motion (μ) | RA: +69.025[8] mas/yr Dec.: −25.496[8] mas/yr |
| Parallax (π) | 7.9685±0.0570 mas[8] |
| Distance | 409 ± 3 ly (125.5 ± 0.9 pc) |
| Absolute magnitude (MV) | +2.20[5] |
| Details | |
| A | |
| Radius | 13.23+0.41 −0.50[7] R☉ |
| Luminosity | 102.4±1.3[7] L☉ |
| Temperature | 5,048+98 −76[7] K |
| Rotational velocity (v sin i) | 1.8[9] km/s |
| Age | 200[5] Myr |
| Other designations | |
| λ Oct, CPD−83°722, GC 30472, HD 206240, HIP 107843, HR 8280, SAO 258914, CCDM J21509-8243, WDS J21509-8243[10] | |
| Database references | |
| SIMBAD | data |
λ Octantis, Latinized as Lambda Octantis, is a binary star[3] system in the southern circumpolar constellation of Octans.[10] It is visible to the naked eye as a dim point of light with a combined apparent visual magnitude of 5.27.[2] The distance to this system is approximately 398–409 light years, based on parallax, but it is moving closer with a radial velocity of −10 km/s.[7]
The primary, designated component A, is an aging, yellow-hued star with a stellar classification of class G8-K0III[11] and a visual magnitude of 5.64.[3] Having exhausted the supply of hydrogen at its core, it has expanded and cooled off the main sequence, becoming a giant. At present it is about 200[5] million years old and has 13[7] times the girth of the Sun. This star is radiating 102[7] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 5,048 K.[7]
The magnitude 7.25[3] secondary companion, component B, is an Am star with a class of kA3hA7VmA8.[5] This notation indicates it has the calcium K line of an A3 class star, the hydrogen lines of a cooler A7 main sequence star, and the metal lines of an A8 star. As of 2008, it lies at an angular separation of 3.233″ from the primary.[3]
