Delta Crucis

  • Imai
  • Delta Crucis
Location of δ Crucis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Crux
Right ascension 12h 15m 08.71673s[1]
Declination −58° 44′ 56.1369″[1]
Apparent magnitude (V) 2.78 - 2.84[2]
Characteristics
Spectral type B2 IV[3]
U−B color index −0.921[4]
B−V color index −0.235[4]
Variable type β Cep[5]
Astrometry
Radial velocity (Rv)+22.2[6] km/s
Proper motion (μ) RA: −35.81[1] mas/yr
Dec.: −10.36[1] mas/yr
Parallax (π)9.45 ± 0.15 mas[1]
Distance345 ± 5 ly
(106 ± 2 pc)
Absolute magnitude (MV)−3.2[7]
Details
Mass8.9±0.1[8] M☉
Radius8.0[9] R☉
Luminosity10,000[7] L☉
Surface gravity (log g)3.88[7] cgs
Temperature22,570±1,840[10] K
Rotational velocity (v sin i)210[11] km/s
Age18.1±3.2[8] Myr
Other designations
Imai, Delta Cru, δ Cru, CD−58 4466, FK5 455, HD 106490, HIP 59747, HR 4656, SAO 239791[12]
Database references
SIMBADdata

Delta Crucis or δ Crucis, also identified as Imai (/ˈiːmaɪ/), is a star in the southern constellation of Crux, and is the faintest of the four bright stars that form the prominent asterism known as the Southern Cross. This star has an apparent magnitude of 2.8, and its proper name was adopted by the International Astronomical Union on 10 August 2018.[13] Imai is a massive, hot and rapidly rotating star that is in the process of evolving into a giant, and is located at a distance of about 345 light-years (106 parsecs) from the Sun.

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