Psi2 Lupi

Psi2 Lupi (ψ2 Lup) is a triple star[7] system in the constellation Lupus. It is visible to the naked eye with an apparent magnitude of 4.75.[2] Based upon an annual parallax shift of 8.97[1] mas as seen from Earth, it is located around 360 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.016±0.009 due to interstellar dust. This system is a member of the Upper Centaurus-Lupus subgroup of the Scorpius–Centaurus Association.[8]

For other star systems with this Bayer designation, see ψ Lupi.
Psi2 Lupi
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Lupus
Right ascension 15h 42m 41.02206s[1]
Declination −34° 42′ 37.4617″[1]
Apparent magnitude (V) 4.75[2]
Characteristics
Spectral type B5 V[3]
U−B color index −0.570[2]
B−V color index −0.146[2]
Variable type Microvariable[3]
Astrometry
Radial velocity (Rv)+3.9±2.8[4] km/s
Proper motion (μ) RA: −21.37[1] mas/yr
Dec.: −29.98[1] mas/yr
Parallax (π)8.97 ± 0.27[1] mas
Distance360 ± 10 ly
(111 ± 3 pc)
Absolute magnitude (MV)−1.44[2]
Orbit[5]
Period (P)12.26 d
Eccentricity (e)0.19
Periastron epoch (T)2438252.97 ± 10.0 JD
Argument of periastron (ω)
(secondary)		82.8°
Semi-amplitude (K1)
(primary)		63.3 km/s
Semi-amplitude (K2)
(secondary)		66.4 km/s
Details
Surface gravity (log g)4.29[3] cgs
Temperature15,135[3] K
Other designations
ψ2 Lup, 4 Lup, CD−34° 10494, HD 140008, HIP 76945, HR 5839, SAO 206889.[6]
Database references
SIMBADdata

The inner pair of stars in this system form a double-lined spectroscopic binary with an orbital period of 12.26 days and an eccentricity of 0.19. The two components are described as similar in appearance.[5] They have the spectrum of a B-type main sequence star with a stellar classification of B5 V.[3] The luminosity has a micro-variability with a frequency of 0.94483 cycles per day and an amplitude of 0.0067 in magnitude.[3] The third component is a magnitude 10 star at an angular separation of 0.51 arc seconds.[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.
  2. Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement, 15: 459, Bibcode:1968ApJS...15..459G, doi:10.1086/190168.
  3. Molenda-Zakowicz, J.; Polubek, G. (December 2005), "New beta Cephei and SPB Stars Discovered in Hipparcos Photometry", Acta Astronomica, 55: 375–388, Bibcode:2005AcA....55..375M.
  4. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  5. Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy & Astrophysics, 424 (2): 727, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213.
  6. "psi02 Lup". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-03-10.
  7. 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.
  8. Chen, Christine H.; et al. (September 2012), "A Spitzer MIPS Study of 2.5-2.0 M⊙ Stars in Scorpius-Centaurus", The Astrophysical Journal, 756 (2): 24, arXiv:1207.3415, Bibcode:2012ApJ...756..133C, doi:10.1088/0004-637X/756/2/133, 133.
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