Lambda Columbae
Variable star in the constellation Columba
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Lambda Columbae is a probable binary star[10] in the southern constellation of Columba. Its name is a Bayer designation that is Latinized from λ Columbae, and abbreviated Lambda Columbae or λ Col. With an apparent visual magnitude of 4.88,[4] it is faintly visible to the naked eye. The measured annual parallax shift of 9.47 mas[2] yields an estimated distance of approximately 345 light-years (106 pc). It is drifting further away from the Sun with a line of sight velocity component of +30 km/s.[6]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Columba[1] |
| Right ascension | 05h 53m 06.882s[2] |
| Declination | −33° 48′ 04.91″[2] |
| Apparent magnitude (V) | 4.88[1] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | B5 V[3] |
| U−B color index | −0.57[4] |
| B−V color index | −0.154±0.008[1] |
| Variable type | Suspected rotating ellipsoidal[5] |
| Astrometry | |
| Radial velocity (Rv) | +30.0[6] km/s |
| Proper motion (μ) | RA: −4.095 mas/yr[2] Dec.: +31.125 mas/yr[2] |
| Parallax (π) | 9.466±0.0901 mas[2] |
| Distance | 345 ± 3 ly (106 ± 1 pc) |
| Absolute magnitude (MV) | −0.17[1] |
| Details | |
| Mass | 4.26±0.04[2] M☉ |
| Radius | 2.72±0.06[2] R☉ |
| Luminosity | 343±6[2] L☉ |
| Surface gravity (log g) | 4.0513±0.009[2] cgs |
| Temperature | 15,057+30 −25[2] K |
| Metallicity [Fe/H] | −0.06[7] dex |
| Rotational velocity (v sin i) | 88[8] km/s |
| Age | 56.6±26.1[3] Myr |
| Other designations | |
| λ Col, CD−33°2599, HD 39764, HIP 27810, HR 2056, SAO 196276[9] | |
| Database references | |
| SIMBAD | data |
Lambda Columbae has a stellar classification of B5 V,[3] indicating that it is a B-type main sequence star. It is a suspected rotating ellipsoidal variable[12] with a period of 0.64 days and an amplitude of 0.07 magnitude.[13] Confirmation would indicate that this is a close binary system.[5]
This star has an estimated age of around 57 million years[3] with a relatively high rate of spin, showing a projected rotational velocity of 88 km/s.[8] It has 4.3 times the mass of the Sun and 2.7 times the Sun's radius. Lambda Columbae is radiating 343 times the luminosity of the Sun from its photosphere at an effective temperature of 15,057 K.[2]
In Chinese, 子 (Zǐ), meaning Son, refers to an asterism consisting of λ Columbae and β Columbae.[14] Consequently, λ Columbae itself is known as 子一 (Zǐ yī, English: the First Star of Son).[15] From this Chinese name, the name Tsze is derived.[16]