Astronomy:Eta Gruis
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Grus |
| Right ascension | 22h 45m 37.88285s[1] |
| Declination | −53° 30′ 00.4405″[1] |
| Apparent magnitude (V) | 4.85[2] |
| Characteristics | |
| Spectral type | K2 III CNIV[3] |
| U−B color index | +1.17[2] |
| B−V color index | +1.18[2] |
| Astrometry | |
| Radial velocity (Rv) | +27.8±2.8[4] km/s |
| Proper motion (μ) | RA: +30.207[1] mas/yr Dec.: +17.921[1] mas/yr |
| Parallax (π) | 7.1001 ± 0.1924[1] mas |
| Distance | 460 ± 10 ly (141 ± 4 pc) |
| Absolute magnitude (MV) | −0.68[5] |
| Details | |
| Radius | 31.38+0.92 −1.04[1] R☉ |
| Luminosity | 338.5±10.5[1] L☉ |
| Temperature | 4,420+75 −64[1] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta Gruis, Latinized from η Gruis, is a solitary[7] star in the southern constellation of Grus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.85.[2] Based upon an annual parallax shift of 7.1 mas as seen from the Earth,[8] the system is located about 460 light years from the Sun. The star is drifting further away with a radial velocity of +28 km/s.[4]
This object is an evolved K-type giant star with a stellar classification of K2 III CNIV,[3] where the suffix notation indicates this is an intermediate CN star. It is a periodic microvariable with an amplitude of 0.0055 magnitude and a frequency of 0.36118 cycles per day.[9] With the supply of hydrogen exhausted at its core, the star has expanded and cooled, now having 31[1] times the Sun's girth. It is radiating 338.5[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,420 K.[1]
Eta Gruis has a magnitude 11.5 visual companion located at an angular separation of 25.6″ along a position angle of 187°, as of 2012.[10]
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 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 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99): 99, Bibcode: 1966CoLPL...4...99J.
- ↑ 3.0 3.1 Houk, Nancy; Cowley, A. P. (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode: 1978mcts.book.....H.
- ↑ 4.0 4.1 Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ "eta Gru". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=eta+Gru.
- ↑ 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.
- ↑ van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ Koen, Chris; Eyer, Laurent (2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society 331 (1): 45–59, doi:10.1046/j.1365-8711.2002.05150.x, Bibcode: 2002MNRAS.331...45K.
- ↑ Mason, B. D. et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal 122 (6): 3466, doi:10.1086/323920, Bibcode: 2001AJ....122.3466M.
 |  |
