Astronomy:Pi2 Gruis
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| 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 |
| Distance | 129.9 ± 0.6 ly (39.8 ± 0.2 pc) |
| Absolute magnitude (MV) | 2.62[7] |
| Details | |
| π2 Gru A | |
| Mass | 1.37[8] M☉ |
| Radius | 1.93±0.07[1] R☉ |
| Luminosity | 7.15±0.04[1] L☉ |
| Surface gravity (log g) | 4.20[8] cgs |
| Temperature | 6788+138 −101[1] K |
| Metallicity [Fe/H] | −0.06[6] dex |
| Age | 758[8] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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
- ↑ 1.00 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. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 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, Bibcode: 1983SAAOC...7...36C.
- ↑ 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, Bibcode: 2008MNRAS.389..869E.
- ↑ 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, Bibcode: 1975AJ.....80..637M.
- ↑ 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, Bibcode: 1978mcts.book.....H.
- ↑ 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, Bibcode: 2011A&A...530A.138C.
- ↑ 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, Bibcode: 2009A&A...501..941H.
- ↑ 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, Bibcode: 2015ApJ...804..146D.
- ↑ "pi.02 Gru". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=pi.02+Gru.
- ↑ 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, Bibcode: 1957MNRAS.117..449D.
- ↑ Renson, P.; Manfroid, J. (2009), "Catalogue of Ap, HGMN and Am stars", Astronomy and Astrophysics 498 (3): 961, doi:10.1051/0004-6361/200810788, Bibcode: 2009A&A...498..961R, https://zenodo.org/record/890529.
- ↑ 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. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
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