Mu Columbae

Mu Columbae

Observation data Epoch J2000      Equinox J2000
Constellation	Columba
Right ascension	05h 45m 59.9s
Declination	-32° 18′ 23″
Apparent magnitude (V)	5.15
Characteristics
Spectral type	O9.5 V
U−B color index	-1.06
B−V color index	-0.28
Variable type	Suspected
Astrometry
Radial velocity (Rv)	+109.2 km/s
Proper motion (μ)	RA: 3.01 mas/yr Dec.: -22.62 mas/yr
Parallax (π)	2.52 ± 0.55 mas
Distance	1300 ly (400 pc)
Absolute magnitude (MV)	-2.84
Details
Mass	12-15 M☉
Radius	4.5 R☉
Luminosity	23,300 L☉
Temperature	33,700 K
Metallicity	?
Rotation	1.5 days (~153 km/s.)
Age	2.7 × 106 years
Other designations
HR 1996, CD -32°2538, HD 38666, SAO 196149, HIP 27204.

Mu Columbae (μ Col, μ Columbae) is a star in the constellation of Columba. It is one of the few O-class stars that is visible to the unaided eye. The star is known to lie approximately 1,300 light years from our solar system (with an error margin of a few hundred light years).

This is a relatively fast rotating star that completes a full revolution approximately every 1.5 days. (Compare this to our Sun, which at only 22% of this star's diameter rotates only once every 25.4 days.) This rate of rotation is fairly typical for stars of this class.

Based on measurements of proper motion and radial velocity, astronomers know that this star and AE Aurigae are moving away from each other at a relative velocity of over 200 km/s. Their common point of origin intersects with Iota Orionis in the Trapezium cluster, some two and half million years in the past. The most likely scenario that could have created these runaway stars is a collision between two binary star systems, with the stars being ejected along different trajectories radial to the point of intersection.

Etymology

In Chinese astronomy, Mu Columbae is called 屎, Pinyin: Shǐ, meaning Excrement, because this star is marking itself and stand alone in Excrement asterism, Three Stars mansion (see : Chinese constellation)^[1]. 屎 (Shǐ) westernized into She by R.H. Allen, with the meaning is "the Secretions" ^[2]

This star, along with ζ CMa, λ CMa, γ Col, δ Col, θ Col, κ Col, λ Col and ξ Col, were Al Ḳurūd (ألقرد - al-qird), the Apes.^[3]

References

• A. Blaauw & W.W. Morgan, 1954, "The Space Motions of AE Aurigae and mu Columbae with Respect to the Orion Nebula", Astrophysical Journal, v.119, p.625.
• R. Hoogerwerf, J.H.J. de Bruijne, P.T. de Zeeuw, 2000, "The origin of runaway stars", Astrophysical Journal, v.544, issue 2, pp. L133-L136.

1. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 15 日
2. ^ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Columbae
3. ^ Davis Jr., G. A., "The Pronunciations, Derivations, and Meanings of a Selected List of Star Names,"Popular Astronomy, Vol. LII, No. 3, Oct. 1944, p. 14.

External links

• Mu Columbae by Professor Jim Kaler.