Lambda Columbae

Lambda Columbae, Latinized from λ Columbae, is a probable binary star^[12] in the southern constellation of Columba. With an apparent visual magnitude of 4.86,^[2] it is faintly visible to the naked eye. The measured annual parallax shift of 9.75 mas^[1] yields an estimated distance of roughly 335 light years.

A light curve for Lambda Columbae, plotted from TESS data.^[13] The 0.64 day period is marked in red.

λ Columbae

Location of λ Columbae (circled in red)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Columba
Right ascension	05h 53m 06.88101s[1]
Declination	−33° 48′ 04.9079″[1]
Apparent magnitude (V)	4.86[2]
Characteristics
Spectral type	B5 V[3]
U−B color index	−0.57[2]
B−V color index	−0.15[2]
Variable type	Suspected rotating ellipsoidal[4]
Astrometry
Radial velocity (Rv)	+30.0[5] km/s
Proper motion (μ)	RA: −4.72[1] mas/yr Dec.: +31.32[1] mas/yr
Parallax (π)	9.75±0.21 mas[1]
Distance	335 ± 7 ly (103 ± 2 pc)
Absolute magnitude (MV)	−0.17[6]
Details
Mass	4.0±0.1[3] M☉
Radius	3.4[7] R☉
Luminosity	213[8] L☉
Surface gravity (log g)	4.22[9] cgs
Temperature	13,524[8] K
Metallicity [Fe/H]	−0.06[9] dex
Rotational velocity (v sin i)	88[10] km/s
Age	56.6±26.1[3] Myr
Other designations
λ Col, CD−33°2599, HD 39764, HIP 27810, HR 2056, SAO 196276.[11]
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^[14] with a period of 0.64 days and an amplitude of 0.07 magnitude.^[15] Confirmation would indicate that this is a close binary system.^[4] It has an estimated age of around 57 million years.^[3]

In Chinese, 子 (Zǐ), meaning Son, refers to an asterism consisting of λ Columbae and β Columbae.^[16] Consequently, λ Columbae itself is known as 子一 (Zǐ yī, English: the First Star of Son).^[17] From this Chinese name, the name Tsze is derived.^[18]