4 Centauri

This article is about h Centauri and is not to be confused with H Centauri.

4 Centauri

Observation data Epoch J2000.0       Equinox J2000.0
Constellation	Centaurus [1]
Right ascension	13h 53m 12.53953s [2]
Declination	−31° 55′ 39.3947″ [2]
Apparent magnitude  (V)	+4.73 [3] (+4.72 [4] / +8.47 [5] )
Characteristics
Spectral type	B6IV [6] / Am [6]
U−B color index	−0.56 [3]
B−V color index	−0.14 [3]
Astrometry
Radial velocity (Rv)	+5.2±2 [7] km/s
Proper motion (μ)	RA: -12.72 [2] mas/yr Dec.: -9.48 [2] mas/yr
Parallax (π)	5.12±0.70  mas [2]
Distance	approx. 640  ly (approx. 200  pc)
Absolute magnitude  (MV)	−1.66 [1]
Orbit [6]
Primary	4 Cen Aa
Companion	4 Cen Ab
Period (P)	6.930137±0.000015 d
Eccentricity (e)	0.25±0.10
Argument of periastron (ω) (secondary)	152±17°
Semi-amplitude (K1) (primary)	21.0±1.5 km/s
Orbit [6]
Primary	4 Cen Ba
Companion	4 Cen Bb
Period (P)	4.8390±0.0001 d
Eccentricity (e)	0.05±0.02
Periastron epoch (T)	2442916.55±0.09
Argument of periastron (ω) (secondary)	51±20°
Semi-amplitude (K1) (primary)	16.9±3.5 km/s
Other designations
h Cen, HD 120955, HR 5221, HIP 67786, CCDM  J13532-3156 [8]
4 Cen A: SAO 204944, GC 18755, CD−31°10729 [9]
4 Cen B: SAO 204943, GC 18754, CD−31°10727 [10]
Database references
SIMBAD	4 Cen
	4 Cen A
	4 Cen B

4 Centauri is a star in the constellation Centaurus. It is a blue-white B-type subgiant with an apparent magnitude of +4.75 and is approximately 640 light years from Earth.

4 Centauri is a hierarchical quadruple star system. The primary component of the system, 4 Centauri A, is a spectroscopic binary, meaning that its components cannot be resolved but periodic Doppler shifts in its spectrum show that it must be orbiting. 4 Centauri A has an orbital period of 6.927 days and an eccentricity of 0.23. Because light from only one of the stars can be detected (i.e. it is a single-lined spectroscopic binary), some parameters such as its inclination are unknown. ^[11] The secondary component, is also a single-lined spectroscopic binary. It has an orbital period of 4.839 days and an eccentricity of 0.05. The secondary component is a metallic-lined A-type star. The two pairs themselves are separated by 14 arcseconds; one orbit would take at least 55,000 years. ^[6]

References

1. 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. XHIP record for this object at VizieR.
2. 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
3. Mendoza, E. E. (1974). "Multicolor photometry of metallic-line stars. III. A photometric catalogue". Revista Mexicana de Astronomía y Astrofísica. 1: 175. Bibcode:1974RMxAA...1..175M. Color indices accessed using SIMBAD.
4. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (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 .
5. Nicolet, B. (1978). "Catalogue of homogeneous data in the UBV photoelectric photometric system". Astronomy and Astrophysics. 34: 1. Bibcode:1978A&AS...34....1N.
6. Levato, H.; Malaroda, S.; Morrell, N.; Solivella, G. (1987). "Stellar multiplicity in the Scorpius-Centaurus association". Astrophysical Journal Supplement Series. 64: 487–503. Bibcode:1987ApJS...64..487L. doi:10.1086/191204.
7. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
8. "* 4 Cen". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 8 February 2018.
9. "* 4 Cen A". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 8 February 2018.
10. "* 4 Cen B". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 8 February 2018.
11. Paddock, G. F. (1917). "The Spectroscopic Binary H 4 Centauri". Publications of the Astronomical Society of the Pacific. 29 (167): 56. Bibcode:1917PASP...29...56P. doi:10.1086/122588. S2CID   120812946.