Astronomy:Pi2 Gruis

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Short description: Binary star system in the constellation Grus


Pi2 Gruis
Observation data
Equinox J2000.0]] (ICRS)
Constellation Grus
Right ascension  22h 23m 07.98704s[1]
Declination −45° 55′ 42.5582″[1]
Apparent magnitude (V) 5.622[2] (5.71 + 11.3)[3]
Characteristics
Spectral type F3 III-IV[4][3] or F0 V[5]
U−B color index +0.016[2]
B−V color index +0.365[2]
Astrometry
Radial velocity (Rv)3.0[6] km/s
Proper motion (μ) RA: +233.166[1] mas/yr
Dec.: −58.205[1] mas/yr
Parallax (π)25.1061 ± 0.1256[1] mas
Distance129.9 ± 0.6 ly
(39.8 ± 0.2 pc)
Absolute magnitude (MV)2.62[7]
Details
π2 Gru A
Mass1.37[8] M
Radius1.93±0.07[1] R
Luminosity7.15±0.04[1] L
Surface gravity (log g)4.20[8] cgs
Temperature6788+138
−101
[1] K
Metallicity [Fe/H]−0.06[6] dex
Age758[8] Myr
Other designations
π2 Gru, CD−46°14295, FK5 3786, HD 212132, HIP 110506, HR 8524, SAO 231111, WDS J22231-4556[9]
Database references
SIMBADdata

π2 Gruis, Latinised as Pi2 Gruis, is a binary star[3] 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.[2] Based upon an annual parallax shift of 25.1 mas as seen from the Earth,[1] 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,[4] which would indicate an evolving subgiant/giant star hybrid spectrum, whereas Houk (1978) listed it as class F0 V,[5] suggesting that it is an F-type main sequence star. It has been considered to be a chemically peculiar star,[10] but this is now considered doubtful.[11] It is 758[8] million years old with 1.4[8] times the mass of the Sun. The star is 1.9[1] times the Sun's radius and is radiating 7[1] times the luminosity of the Sun from its photosphere at an effective temperature of 6,788 K.[1]

The companion is a magnitude 11.3 star at an angular separation of 4.6 arc seconds.[3] 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.[12]

References

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. 2.0 2.1 2.2 2.3 Cousins, A. W. J. (1983), "UBV photometry of E region standard stars of intermediate brightness", South African Astronomical Observatory Circular 7 (7): 36–46, Bibcode1983SAAOC...7...36C. 
  3. 3.0 3.1 3.2 3.3 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode2008MNRAS.389..869E. 
  4. 4.0 4.1 Malaroda, S. (August 1975), "Study of the F-type stars. I. MK spectral types", Astronomical Journal 80: 637–641, doi:10.1086/111786, Bibcode1975AJ.....80..637M. 
  5. 5.0 5.1 Houk, N. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 2, Dept. of Astronomy, University of Michigan, Bibcode1978mcts.book.....H. 
  6. 6.0 6.1 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, doi:10.1051/0004-6361/201016276, Bibcode2011A&A...530A.138C. 
  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, doi:10.1051/0004-6361/200811191, Bibcode2009A&A...501..941H. 
  8. 8.0 8.1 8.2 8.3 8.4 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, doi:10.1088/0004-637X/804/2/146, Bibcode2015ApJ...804..146D. 
  9. "pi.02 Gru". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=pi.02+Gru. 
  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, doi:10.1093/mnras/117.4.449, Bibcode1957MNRAS.117..449D. 
  11. Renson, P.; Manfroid, J. (2009), "Catalogue of Ap, HGMN and Am stars", Astronomy and Astrophysics 498 (3): 961, doi:10.1051/0004-6361/200810788, Bibcode2009A&A...498..961R, https://zenodo.org/record/890529/files/article.pdf. 
  12. Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.