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π Gruis, Latinised as Pi Gruis, is a binary star system in the southern constellation of Grus. It is faintly visible to the naked eye as a yellow-white hued star with an apparent visual magnitude of 5.622. Based upon an annual parallax shift of 25.1 mas as seen from the Earth, the system is located 130 light years from the Sun.

The primary, component A, is an F-type star of uncertain luminosity class. Malaroda (1975) gave it a stellar classification of F3 III-IV, which would indicate an evolving subgiant/giant star hybrid spectrum, whereas Houk (1978) listed it as class F0 V, suggesting that it is an F-type main sequence star. It has been considered to be a chemically peculiar star, but this is now considered doubtful. It is 758 million years old with 1.4 times the mass of the Sun. The star is 1.9 times the Sun's radius and is radiating 7 times the luminosity of the Sun from its photosphere at an effective temperature of 6,788 K.

The companion is a magnitude 11.3 star at an angular separation of 4.6 arc seconds. Gaia Data Release 2 has measured a separate annual parallax for it of 25.3266±0.0871 mas, almost identical to the primary star, and indicates that it is a red dwarf.

References

1. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
2. ^ Cousins, A. W. J. (1983), "UBV photometry of E region standard stars of intermediate brightness", South African Astronomical Observatory Circular, 7 (7): 36–46, Bibcode:1983SAAOC...7...36C.
3. ^ 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, S2CID 14878976.
4. ^ Malaroda, S. (August 1975), "Study of the F-type stars. I. MK spectral types", Astronomical Journal, 80: 637–641, Bibcode:1975AJ.....80..637M, doi:10.1086/111786.
5. ^ Houk, N. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 2, Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
6. ^ Casagrande, L.; et al. (2011), "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey", Astronomy & Astrophysics, 530 (A138): 21, arXiv:1103.4651, Bibcode:2011A&A...530A.138C, doi:10.1051/0004-6361/201016276, S2CID 56118016.
7. Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191, S2CID 118577511.
8. ^ David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
9. "pi.02 Gru". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-25.{{cite web}}: CS1 maint: postscript (link)
10. De Vaucouleurs, A. (1957), "Spectral types and luminosities of B, A and F southern stars", Monthly Notices of the Royal Astronomical Society, 117 (4): 449–462, Bibcode:1957MNRAS.117..449D, doi:10.1093/mnras/117.4.449.
11. Renson, P.; Manfroid, J. (2009), "Catalogue of Ap, HGMN and Am stars", Astronomy and Astrophysics, 498 (3): 961, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.
12. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.

v t e Constellation of Grus
List of stars in Grus List of star names in Grus Grus in Chinese astronomy
Stars	Bayer α (Alnair) β (Tiaki) γ (Aldhanab) δ δ ε ζ η θ ι κ λ μ μ ν ξ ο π π ρ σ σ τ τ τ υ φ Variable RZ CE HR 8323 8501 HD 208487 (Itonda) 213240 215456 Other 2MASS J22282889–4310262 Gliese 832 PSR J2144−3933 S5-HVS1 WASP-95 WISE 2220−3628
Exoplanets Gliese 832 b HD 208487 b HD 213240 b τ Gruis b
Galaxies	NGC 7070 7070A 7072 7075 7079 7087 7213 7418 7424 7496 7531 7552 7582 7590 Other IC 1459 IC 5201
Galaxy clusters Abell S1063
Category

• F-type stars
• Binary stars
• Grus (constellation)
• Bayer objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Bright Star Catalogue objects
• Durchmusterung objects