Pi Centauri

Pi Centauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Centaurus
Right ascension 11h 21m 00.41s[1]
Declination −54° 29′ 27.7″[1]
Apparent magnitude (V) +3.90[2] (4.08 + 5.65)[3]
Characteristics
Spectral type B5Vn[4] + B6V[5]
B−V color index −0.157±0.015[2]
Astrometry
Radial velocity (Rv)+9.4±3.7[2] km/s
Proper motion (μ) RA: −35.85±0.34[1] mas/yr
Dec.: −1.72±0.27[1] mas/yr
Parallax (π)9.12 ± 0.34 mas[1]
Distance360 ± 10 ly
(110 ± 4 pc)
Absolute magnitude (MV)−1.30[2]
Orbit[6]
Period (P)39.0±0.19 yr
Semi-major axis (a)0.2263±0.0011″
Eccentricity (e)0.8530±0.0040
Inclination (i)19.4±4.9°
Longitude of the node (Ω)327.8±3.9°
Periastron epoch (T)2010.410±0.037
Argument of periastron (ω)
(secondary)		340.3±4.0°
Details
A
Mass6.43[6] M☉
Temperature16,760[7] K
Rotational velocity (v sin i)340[8] km/s
B
Mass3.68[6] M☉
Other designations
π Cen, BD−53°4498, FK5 428, GC 15601, HD 98718, HIP 55425, HR 4390, SAO 238986, CCDM J11210-5429[9]
Database references
SIMBADdata

Pi Centauri, Latinized from π Centauri, is a binary star system in the southern constellation of Centaurus. It has a blue-white hue and is visible to the naked eye with a combined apparent visual magnitude of +3.90.[2] The system is located at a distance of approximately 360 light years from the Sun based on parallax,[1] and is drifting further away with a radial velocity of around +9 km/s.[2] It is a member of the Lower Centaurus–Crux subgroup of the Scorpius–Centaurus association.[10]

The magnitude +4.08[3] primary, designated component A, is a B-type main-sequence star with a stellar classification of B5Vn,[4] where the 'n' suffix indicates broad, diffuse (nebulous) lines due to rapid rotation. This star is spinning with a projected rotational velocity of 340 km/s, giving it an equatorial bulge that is 22% larger than the polar radius.[8] It has 6.4[6] times the mass of the Sun and is radiating 783[2] times the Sun's luminosity from its photosphere at an effective temperature of 16,760 K.[7]

The secondary companion, component B, is magnitude +5.65[3] with a class of B6V[5] and 3.7[6] times the Sun's mass. The pair orbit around their common barycentre once every 39 years with an eccentricity of 0.8530. The semi-major axis of the companion is 0.23 arcseconds at an inclination of 19.4°.[6]

  1. ^ a b c d e f Cite error: The named reference van Leeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d e f g Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Mason2001 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Hiltner1969 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Edwards1976 was invoked but never defined (see the help page).
  6. ^ a b c d e f Cite error: The named reference Tokovinin2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Zorec2009 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference vanBelle2012 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).
  10. ^ Cite error: The named reference Bobylev2007 was invoked but never defined (see the help page).