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Pi Centauri

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Pi Centauri

Observation data
Epoch J2000.0 Equinox J2000.0

11^h21^m 00.41^s^[1]

−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 (R_v)

+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]

Distance

360 ± 10 ly
(110 ± 4 pc)

Absolute magnitude (M_V)

−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

Mass

6.43^[6] M_☉

Temperature

16,760^[7] K

Rotational velocity (v sin i)

340^[8] km/s

Mass

3.68^[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

SIMBAD

data

Pi Centauri, Latinized from π Centauri, is a binary star system in the southern constellationofCentaurus. 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]

References[edit]

^ ^a ^b ^c ^d ^e ^f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.Vizier catalog entry

^ ^a ^b ^c ^d ^e ^f ^g Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.

^ ^a ^b ^c Mason, Brian D.; et al. (2001), "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.

^ ^a ^b Hiltner, W. A.; et al. (July 1969), "MK Spectral Types for Bright Southern OB Stars", Astrophysical Journal, 157: 313–326, Bibcode:1969ApJ...157..313H, doi:10.1086/150069.

^ ^a ^b Edwards, T. W. (1976), "MK classification for visual binary components", The Astronomical Journal, 81: 245–249, Bibcode:1976AJ.....81..245E, doi:10.1086/111879.

^ ^a ^b ^c ^d ^e ^f Tokovinin, Andrei (2012), "Speckle Interferometry and Orbits of "Fast" Visual Binaries", The Astronomical Journal, 144 (2), 56, arXiv:1206.1882, Bibcode:2012AJ....144...56T, doi:10.1088/0004-6256/144/2/56, S2CID 118586009.

^ ^a ^b Zorec, J.; et al. (July 2009), "Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into Teff", Astronomy and Astrophysics, 501 (1): 297–320, arXiv:0903.5134, Bibcode:2009A&A...501..297Z, doi:10.1051/0004-6361/200811147, S2CID 14969137.

^ ^a ^b van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474.

^ "pi Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-10.

^ Bobylev, V. V.; Bajkova, A. T. (September 2007), "Kinematics of the Scorpius–Centaurus OB association", Astronomy Letters, 33 (9): 571–583, arXiv:0708.0943, Bibcode:2007AstL...33..571B, doi:10.1134/S1063773707090010, S2CID 15785349.