Tau2 Gruis

Tau2 Gruis (Tau2 Gruis), is a double star located in the constellation Grus. The somewhat faint double star can be located west of Beta Gruis. As of 2015, the pair had an angular separation of 0.60 arc seconds along a position angle of 176°.[3] The system is 156 light years from Earth. The two stars were assigned the designation Tau2 due to their proximity to Tau3 Grus, by Louis de Lacaille in his Coelum Australe Stelliferum.

For other stars with this Bayer designation, see τ Gruis.
Tau2 Gruis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Grus
Right ascension  22h 55m 16.14624s[1]
Declination −48° 27′ 56.8622″[1]
Apparent magnitude (V) 7.035[2] (7.29 + 8.91)[3]
Characteristics
Spectral type G3/6[4]
Astrometry
Radial velocity (Rv)0.9[5] km/s
Proper motion (μ) RA: −227.04[1] mas/yr
Dec.: +62.29[1] mas/yr
Parallax (π)20.97 ± 0.84[1] mas
Distance156 ± 6 ly
(48 ± 2 pc)
Absolute magnitude (MV)3.64[2]
Details[5]
Mass1.11 M☉
Surface gravity (log g)4.10 cgs
Temperature6,008 K
Metallicity [Fe/H]−0.19 dex
Age6.3 Gyr
Other designations
τ2 Gru, CD−49° 13996, HD 216655, HIP 113191, SAO 231354, WDS J22553-4828[6]
Database references
SIMBADdata

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. 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.
  3. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
  4. 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.
  5. 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.
  6. "HD 216655". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-24.
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