Psi Centauri

Psi Centauri, which is Latinized from ψ Centauri, is a binary star[10] system in the southern constellation of Centaurus. It is visible to the naked eye with a baseline apparent visual magnitude of +4.05.[2] The distance to this system is approximately 259 light years based on parallax.[1] The radial velocity is poorly constrained, but it appears to be slowly drifting away from the Sun at the rate of +2 km/s.[5]

Psi Centauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Centaurus
Right ascension 14h 20m 33.43s[1]
Declination −37° 53′ 07.1″[1]
Apparent magnitude (V) +4.05[2]
Characteristics
Spectral type A0 IV[3] (B9 and A2)[4]
U−B color index −0.11[3]
B−V color index −0.03[3]
Variable type eclipsing[4]
Astrometry
Radial velocity (Rv)1.8±0.9[5] km/s
Proper motion (μ) RA: −63.69±0.18[1] mas/yr
Dec.: −10.65±0.15[1] mas/yr
Parallax (π)12.60 ± 0.20[1] mas
Distance259 ± 4 ly
(79 ± 1 pc)
Absolute magnitude (MV)−0.35±0.14[6]
Orbit[4]
Period (P)38.81252±0.00029 d
Eccentricity (e)0.55408±0.00024
Inclination (i)88.955±0.012°
Argument of periastron (ω)
(secondary)		20.095±0.098°
Semi-amplitude (K1)
(primary)		49.01±0.11[7] km/s
Semi-amplitude (K2)
(secondary)		79.92±0.15[7] km/s
Details
ψ Cen A
Mass3.114[8] M☉
Radius3.634[8] R☉
Luminosity141[8] L☉
Surface gravity (log g)3.811±0.003[7] cgs
Temperature10,450[8] K
Rotation1.49±0.26 d[4]
Rotational velocity (v sin i)123.7[7] km/s
Age269[6] Myr
ψ Cen B
Mass1.909[8] M☉
Radius1.811[8] R☉
Luminosity18[8] L☉
Surface gravity (log g)4.206±0.007[7] cgs
Temperature8,800[8] K
Rotational velocity (v sin i)126.9[7] km/s
Other designations
ψ Cen, CD−37° 9336, FK5 1373, GC 19337, HD 125473, HIP 70090, HR 5367, SAO 205453, CCDM J14206-3753, WDS J14206-3753[9]
Database references
SIMBADdata

This is a detached eclipsing binary system with the secondary eclipse being total.[4] The pair are orbiting each other with a period of 38.81 days and an eccentricity of 0.55.[10] The brightness of the system dips by 0.28 and 0.16 magnitude during the two eclipses per orbit.[4] The system displays an infrared excess at a wavelength of 60 μm, indicating the presence of a circumstellar debris disk with a temperature of 120 K, orbiting at a distance of 64 AU.[11]

The pair have a combined stellar classification of A0 IV,[3] matching a white-hued A-type subgiant.[2] The two components appear to be at different evolutionary stages.[4] Both have high rotation rates, with projected rotational velocities over 120 km/s.[7] The primary has 3.6 times the Sun's radius while the secondary is 1.8 times.[8] The primary showed evidence of pulsational behavior with 1.996 and 5.127 cycles per day,[4] which suggests it is a slowly pulsating B star.[7] But this remains unconfirmed as of 2017,[12] and the finding may instead be the result of instrumental error.[7]

References
  1. 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. Vizier catalog entry
  2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J.
  3. Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4, Bibcode:1962MtSOM...4....1B.
  4. Bruntt, H.; et al. (September 2006), "Eclipsing binaries observed with the WIRE satellite. I. Discovery and photometric analysis of the new bright A0 IV eclipsing binary ψ Centauri", Astronomy and Astrophysics, 456 (2): 651–658, arXiv:astro-ph/0606551, Bibcode:2006A&A...456..651B, doi:10.1051/0004-6361:20065628.
  5. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065.
  6. Gerbaldi, M.; et al. (June 1999), "Search for reference A0 dwarf stars: Masses and luminosities revisited with HIPPARCOS parallaxes", Astronomy and Astrophysics Supplement, 137 (2): 273–292, Bibcode:1999A&AS..137..273G, doi:10.1051/aas:1999248.
  7. Mantegazza, L.; et al. (March 2010), "Spectroscopic search for g-mode pulsations in ψ Centauri", Astronomy and Astrophysics, 512: 5, Bibcode:2010A&A...512A..42M, doi:10.1051/0004-6361/200913013, A42.
  8. Eker, Z.; et al. (April 2015), "Main-Sequence Effective Temperatures from a Revised Mass-Luminosity Relation Based on Accurate Properties", The Astronomical Journal, 149 (4): 16, arXiv:1501.06585, Bibcode:2015AJ....149..131E, doi:10.1088/0004-6256/149/4/131, 131.
  9. "psi Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-30.
  10. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  11. Rhee, Joseph H.; et al. (May 2007), "Characterization of Dusty Debris Disks: The IRAS and Hipparcos Catalogs", The Astrophysical Journal, 660 (2): 1556–1571, arXiv:astro-ph/0609555, Bibcode:2007ApJ...660.1556R, doi:10.1086/509912.
  12. Liakos, Alexios; Niarchos, Panagiotis (February 2017), "Catalogue and properties of δ Scuti stars in binaries", Monthly Notices of the Royal Astronomical Society, 465 (1): 1181–1200, arXiv:1611.00200, Bibcode:2017MNRAS.465.1181L, doi:10.1093/mnras/stw2756.
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