Beta Crucis

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**β Cru A/B**
Observation data Epoch J2000
Becrux
Constellation (pronunciation)	Crux
Right ascension	12h 47m 43.2s
Declination	−59° 41' 19"
Apparent magnitude (V)	1.30
Characteristics
Spectral type	B0.5 IV
U-B color index	−1.00
B-V color index	−0.15
Variable type	Beta Cephei
Astrometry
Radial velocity (R_v)	+15.6 km/s
Proper motion (μ)	RA: −48.24 mas/yr Dec.: −12.82 mas/yr
Parallax (π)	9.25 ± 0.61 mas
Distance	350 ± 20 ly (108 ± 7 pc)
Absolute magnitude (M_V)	−3.92
Details
Mass	14 M_☉
Radius	8 R_☉
Luminosity	34,000 L_☉
Temperature	28,200 K
Metallicity	80% Sun
Age	10 million years
Visual binary orbit
Companion	β Cru B
Period (P)	4.0 yr
Semimajor axis (a)	8.0 AU"
Eccentricity (e)	0
Inclination (i)	0°
Longitude of the node (Ω)	0°
Periastron epoch (T)	0
Other designations
Mimosa, Becrux, β Crucis, HR 4853, CPD P-59°4451, HD 111123, FK5 481, SAO 240259, HIP 62434.
Database references
SIMBAD	data

Mimosa or Becrux (β Cru / β Crucis / Beta Crucis) is the second brightest star in the constellation Crux (after Alpha Crucis or Acrux) and is one of the brightest stars in the nighttime sky.

Beta Crucis is located approximately 353 light years distant. It is a spectroscopic binary with components that are too close together to resolve with a telescope. The pair orbit each other every 5 years and are separated by about 8 AU. Beta Crucis, being of spectral type B0.5IV, is believed to be the hottest first-magnitude star.

Since Beta Crucis is at roughly −60° declination, it is only visible south of the Tropic of Cancer and therefore didn't receive a known ancient traditional name. "Mimosa" is a recent name based on its color, while "Becrux" is simply a combination of the "Be" in Beta plus Crux. It is known as 十字架三 (the Third Star of the Cross) in Chinese.