Beta Carinae

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Beta Carinae
Observation data
Epoch J2000
Constellation
(pronunciation)		 Carina
Right ascension 09h 13m 12.0s
Declination -69° 43' 02"
Apparent magnitude (V) 1.67
Characteristics
Spectral type A2 IV
U-B color index 0.03
B-V color index 0.00
Variable type None
Astrometry
Radial velocity (Rv) -5.2 km/s
Proper motion (μ) RA: -157.66 mas/yr
Dec.: 108.91 mas/yr
Parallax (π) 29.34 ± 0.47 mas
Distance 111 ± 2 ly
(34.1 ± 0.5 pc)
Absolute magnitude (MV) -1.00
Details
Mass 3 M☉
Radius 5.7 R☉
Luminosity 210 L☉
Temperature 9,100 K
Metallicity ?
Rotation 2.1 days
Age 3.5 × 108 years
Other designations
Miaplacidus, Gl 339.2, HR 3685, CD−69°600, HD 80007, GCTP 2213.00, SAO 250495, FK5 348, CP−69°1023, HIP 45238, GC 12764

Beta Carinae (β Car / β Carinae) is the second brightest star in the constellation Carina and one of the brightest stars in the nighttime sky, with apparent magnitude 1.68. It is the brightest star in the south polar asterism known as the Diamond Cross, marking the southwestern end of the asterism. Beta Carinae also has the traditional name Miaplacidus, meaning "placid waters".

Beta Carinae's traditional name Miaplacidus made its debut on star maps in 1856 when the star atlas Geography of the Heavens, composed by Elijah Hinsdale Burritt, was published. The meaning and lingusitic origin of the name remained an enigma for many decades, until William Higgins, a great scholar and expert on star names, surmised that the name Miaplacidus is apparently a bilingual combination of Arabic مياه miyāh for "waters" and Latin placidus for "placid".

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