Mu Crucis

Mu Crucis

Observation data Epoch J2000      Equinox
Constellation	Crux
μ1 Crucis
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	4.03
μ2 Crucis
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	5.19
Characteristics
μ1 Cru
Spectral type	B2IV-V
U−B Template:Engvar	−0.75
B−V Template:Engvar	−0.17
μ2 Cru
Spectral type	B5Vne
U−B Template:Engvar	−0.50
B−V Template:Engvar	−0.11
Astrometry
μ1 Cru
Radial velocity (Rv)	+13.9 km/s
Proper motion (μ)	RA: −30.45 mas/yr Dec.: −13.55 mas/yr
Parallax (π)	9.6267±0.3611 mas
Distance	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	−1.49
μ2 Cru
Radial velocity (Rv)	+13 km/s
Proper motion (μ)	RA: −32.35 mas/yr Dec.: −10.93 mas/yr
Parallax (π)	8.9486±0.2264 mas
Distance	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	−0.40
Details
μ1 Cru
Mass	7.7 Template:Solar mass
Luminosity	1,123 Template:Solar luminosity
Surface gravity (log g)	3.93 cgs
Temperature	21,100 K
Metallicity [Fe/H]	−0.21 dex
Age	9.2 Myr
μ2 Cru
Mass	5.0 Template:Solar mass
Radius	3.9 Template:Solar radius
Luminosity	205 Template:Solar luminosity
Surface gravity (log g)	3.40 cgs
Temperature	20,400 K
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Rotational velocity (v sin i)	210 km/s
Age	15.9 Myr
Other designations
μ Cru, WD 12546-5711, CCDM 12546-5711
μ1 Cru: HR 4898, CD−56°4688, HD 112092, SAO 240366, HIP 63003
μ2 Cru: HR 4899, CD−56°4689, HD 112091, SAO 240367, HIP 63005
Database references
SIMBAD	μ Cru
	μ1 Cru
	μ2 Cru

Mu Crucis, Latinized from μ Crucis, is the seventh-brightest star in the constellation Crux commonly known as the Southern Cross. μ Crucis is a wide double star of spectral class B stars, magnitude 4.0 and 5.2 respectively. They lie about 370 light-years away, and both stars are likely physically attached. The brighter component is known as μ¹ Crucis or μ Crucis A, while the fainter is μ² Crucis or μ Crucis B.

μ¹ Crucis is the brighter of the two stars with an apparent magnitude of 4.0. It is a hot massive main sequence or subgiant star, over a thousand times as luminous as the sun.

μ² Crucis is the fainter of the pair. Its apparent magnitude is 5.2 and it is a Be star, a star spinning so quickly that it has ejected a disc of material that creates emission lines in its spectrum. The disc is inclined at 36° to our line of sight.