Beta Centauri

β Centauri/Hadar
Location of β Centauri (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension 14h 03m 49.40535s[1]
Declination −60° 22′ 22.9266″[1]
Apparent magnitude (V) 0.61[2]
Characteristics
U−B color index –0.98[2]
B−V color index –0.23[2]
β Cen Aa
Spectral type B1 III[3]
Variable type β Cep/SPB[4]
β Cen Ab
Spectral type B1 III[3]
β Cen B
Spectral type B1V?[3]
Astrometry
Radial velocity (Rv)+9.59+0.23
−0.21
[4] km/s
Proper motion (μ) RA: –33.27 mas/yr[1]
Dec.: –23.16 mas/yr[1]
Parallax (π)9.04 ± 0.04 mas[4]
Distance361 ± 2 ly
(110.6 ± 0.5 pc)[4]
Absolute magnitude (MV)−4.9±0.2[5]
Orbit[4]
Primaryβ Cen Aa
Companionβ Cen Ab
Period (P)356.915±0.015 d
(0.97720±0.00004 yr)
Semi-major axis (a)0.02515+0.09
−0.08
Eccentricity (e)0.8245±0.006
Inclination (i)67.68±0.12°
Longitude of the node (Ω)108.80+0.14
−0.15
°
Periastron epoch (T)2452000.15202
Argument of periastron (ω)
(secondary)
60.87+0.26
−0.25
°
Semi-amplitude (K1)
(primary)
62.9 km/s
Semi-amplitude (K2)
(secondary)
72.35 km/s
Orbit[6]
Primaryβ Cen A
Companionβ Cen B
Period (P)288.267 yr
Semi-major axis (a)0.870″
Details
β Cen Aa
Mass12.02±0.13[4] M
Radius9.16[note 1] R
Luminosity31,600+18,500
−11,700
[5] L
Surface gravity (log g)3.55±0.11[5] cgs
Temperature25,000±2,000[5] K
Rotational velocity (v sin i)190±20[7] km/s
Age14.1±0.6[3] Myr
β Cen Ab
Mass10.58±0.18[4] M
Radius8.56[note 1] R
Luminosity25,100+14,700
−9,300
[5] L
Surface gravity (log g)3.55±0.11[5] cgs
Temperature23,000±2,000[5] K
Rotational velocity (v sin i)75±15[7] km/s
Age14.1±0.6[3] Myr
β Cen B
Mass4.61[6] M
Age14.1±0.6[3] Myr
Other designations
Agena, Hadar[8], CD−59°5365, FK5 518, GC 18971, HD 122451, HIP 68702, HR 5267, SAO 252582, CCDM J14038-6022, LHS 51[9]
Database references
SIMBADdata

Beta Centauri is a triple star system in the southern constellation of Centaurus. It is officially called Hadar (/ˈhdɑːr/). The Bayer designation of Beta Centauri is Latinised from β Centauri, and abbreviated Beta Cen or β Cen. The system's combined apparent visual magnitude of 0.61 makes it the second-brightest object in Centaurus and the eleventh brightest star in the night sky. According to dynamical parallax measurements, the distance to this system is about 361 light-years (111 parsecs).

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  2. ^ a b c Cite error: The named reference hr was invoked but never defined (see the help page).
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  4. ^ a b c d e f g Cite error: The named reference Pigulski16 was invoked but never defined (see the help page).
  5. ^ a b c d e f g Cite error: The named reference schultz2019 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference msc was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference alecian2011 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference allen1963 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).


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