Delta1 Gruis

Delta1 Gruis, Latinized from δ1 Gruis, is a candidate binary star[8] system in the constellation Grus. With a peak apparent visual magnitude of 3.97,[2] it is bright enough to be seen with the naked eye at night. The distance to this system, as determined using an annual parallax shift of 10.54 mas as seen from the Earth,[1] is around 309 light years. It is gradually moving away from the Sun with a radial velocity of +4.9 km/s.[4]

For other stars with this Bayer designation, see δ Gruis.
Delta1 Gruis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Grus
Right ascension  22h 29m 16.17481s[1]
Declination −43° 29′ 44.0245″[1]
Apparent magnitude (V) 3.97[2]
Characteristics
Spectral type G6/8 III[3]
U−B color index +0.81[2]
B−V color index +1.03[2]
Astrometry
Radial velocity (Rv)+4.9±0.8[4] km/s
Proper motion (μ) RA: +25.72[1] mas/yr
Dec.: −3.32[1] mas/yr
Parallax (π)10.54 ± 0.22[1] mas
Distance309 ± 6 ly
(95 ± 2 pc)
Absolute magnitude (MV)−0.91[5]
Details
Luminosity288[5] L☉
Surface gravity (log g)2.54±0.28[6] cgs
Temperature5,013±88[6] K
Metallicity [Fe/H]−0.23±0.09[6] dex
Other designations
δ1 Gru, CD−44° 14931, FK5 846, HD 213009, HIP 110997, HR 8556, SAO 231154, WDS J22293-4330A[7]
Database references
SIMBADdata

The brighter component of this system is an evolved, yellow-hued, G-type giant star with a stellar classification of G6/8 III.[3] It is a semiregular variable that ranges between apparent magnitudes 3.99 and 4.2,[9] located 325 light-years from Earth. Delta1 Gruis has around 3 times the mass and 135 times the diameter of the Sun.[10] The fainter companion is a magnitude 12.8 star at an angular separation of 5.6 arc seconds, as of 2008.[8]

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. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J.
  3. 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.
  4. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065.
  5. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  6. Alves, S.; et al. (April 2015), "Determination of the spectroscopic stellar parameters for 257 field giant stars", Monthly Notices of the Royal Astronomical Society, 448 (3): 2749–2765, arXiv:1503.02556, Bibcode:2015MNRAS.448.2749A, doi:10.1093/mnras/stv189.
  7. "del01 Gru". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-18.
  8. 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.
  9. Watson, Christopher (25 August 2009), "Delta 2 Gruis", AAVSO Website, American Association of Variable Star Observers, retrieved 18 January 2014.
  10. Kaler, James B. "Delta Gruis". Stars. University of Illinois. Retrieved 26 January 2014.
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