| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Columba |
| Right ascension | 06h 10m 10.40393s [2] |
| Declination | −40° 21′ 13.6464″ [2] |
| Apparent magnitude (V) | 5.60 - 5.71 [3] |
| Characteristics | |
| Evolutionary stage | AGB [4] |
| Spectral type | M2 II/III [5] |
| B−V color index | +1.68 [6] |
| Variable type | Lb [7] |
| Astrometry | |
| Radial velocity (Rv) | −19±7.4 [8] km/s |
| Proper motion (μ) | RA: −20.650 mas/yr [2] Dec.: +74.080 mas/yr [2] |
| Parallax (π) | 3.9737±0.0841 mas [2] |
| Distance | 820 ± 20 ly (252 ± 5 pc) |
| Absolute magnitude (MV) | −1.53 [9] |
| Details | |
| Mass | 1.54 [10] M☉ |
| Radius | 148 [11] R☉ |
| Luminosity (bolometric) | 1,853 [12] L☉ |
| Surface gravity (log g) | 0.26 [13] cgs |
| Temperature | 3,611±122 [14] K |
| Other designations | |
| 82 G. Columbae [15] , AF Col, NSV 2864, CD−40°2291, CPD−40°930, GC 7873, HD 42682, HIP 29263, HR 2203, SAO 217753 [16] | |
| Database references | |
| SIMBAD | data |
AF Columbae, also known as HD 42682, is a solitary, [17] red hued variable star located in the southern constellation Columba, the dove. It has an apparent magnitude that fluctuates between 5.6 and 5.71. [3] Nevertheless, it is faintly visible to the naked eye. Parallax measurements from the Gaia spacecraft place the star relatively far at a distance of 820 light years. [2] However, it is approaching the Solar System with a poorly constrained radial velocity of −19 km/s . [8]
AF Columbae is a red giant that is currently on the asymptotic giant branch, [4] generating energy via hydrogen and helium shell burning. It has a stellar classification of M2 II/III, [5] indicating an evolved M-type star with the blended luminosity class of a regular giant star and a bright giant. At present it has 1.54 times the mass of the Sun [10] but has expanded to 148 times its girth. [11] It shines with a bolometric luminosity 1,853 times that of the Sun [12] from its enlarged photosphere at an effective temperature of 3,611 K . [14]
The star was discovered to be a variable star when the Hipparcos data was analyzed. It was given its variable star designation, AF Columbae, in 1999. [18] The object is classified as a slow irregular variable of subtype Lb. [7] Tabur et al. (2009) found 5 periods for AF Columbae. Most of them last for 40-50 days, while one of them last for 112 days. [19] It appears to be a runaway star, having an unusually high peculiar velocity of 93.2+4.6
−5.2 km/s . [20]
