| |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Columba |
| Right ascension | 06h10m 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 velocityof−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 temperatureof3,611 K.[14]
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.[18] It appears to be a runaway star, having an unusually high peculiar velocityof93.2+4.6
−5.2 km/s.[19]
