Delta2 Gruis

Delta² Gruis, Latinized from δ² Gruis, is a solitary,^[11] red-hued star in the southern constellation of Grus. It is visible to the naked eye with an apparent visual magnitude of about 4. Based upon an annual parallax shift of 9.88 mas as seen from the Earth, the star is located around 330 light years from the Sun. It is moving further away from the Sun with a radial velocity of +3 km/s.^[6]

For other stars with this Bayer designation, see δ Gruis.

Delta² Gruis

A light curve for Delta2 Gruis, plotted from Hipparcos data[1]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Grus
Right ascension	22h 29m 45.43402s[2]
Declination	−43° 44′ 57.1968″[2]
Apparent magnitude (V)	3.99 - 4.20[3]
Characteristics
Spectral type	M4.5 IIIa[4]
U−B color index	+1.71[5]
B−V color index	+1.57[5]
Variable type	LB?[3]
Astrometry
Radial velocity (Rv)	+2.7±0.8[6] km/s
Proper motion (μ)	RA: −14.08[2] mas/yr Dec.: +2.57[2] mas/yr
Parallax (π)	9.1556 ± 0.1885 mas[7]
Distance	356 ± 7 ly (109 ± 2 pc)
Absolute magnitude (MV)	−0.90±0.05[4]
Details
Radius	97[8] R☉
Luminosity	1,359[8] L☉
Surface gravity (log g)	+0.45[8] cgs
Temperature	3,560[8] K
Rotational velocity (v sin i)	+4.5±0.8[9] km/s
Other designations
δ2 Gru, CD−44° 14935, HD 213080, HIP 111043, HR 8560, SAO 231161, WDS J22298-4345A[10]
Database references
SIMBAD	data

This is an evolved red giant star with a stellar classification of M4.5 IIIa.^[4] It is a pulsating variable with multiple periods, including 20.6, 24.1, 24.5, and 32.3 days. The strongest period is 33.3 days with an amplitude of 0.043 magnitude.^[12] It has a magnitude 9.71 visual companion at an angular separation of 60.4 arc seconds along a position angle of 210°, as of 2013.^[13]

References

1. "/ftp/cats/more/HIP/cdroms/cats". Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved 15 October 2022.
2. 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, S2CID 18759600.
3. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
4. Park, Sunkyung; et al. (2013), "Wilson-Bappu Effect: Extended to Surface Gravity", The Astronomical Journal, 146 (4): 73, arXiv:1307.0592, Bibcode:2013AJ....146...73P, doi:10.1088/0004-6256/146/4/73, S2CID 119187733.
5. Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
6. 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, S2CID 119231169.
7. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
8. McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017). "Fundamental parameters and infrared excesses of Tycho-Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433.
9. Zamanov, R. K.; et al. (October 2008), "Rotational velocities of the giants in symbiotic stars - III. Evidence of fast rotation in S-type symbiotics", Monthly Notices of the Royal Astronomical Society, 390 (1): 377–382, arXiv:0807.3817, Bibcode:2008MNRAS.390..377Z, doi:10.1111/j.1365-2966.2008.13751.x, S2CID 118697261.
10. "del02 Gru". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-18.{{cite web}}: CS1 maint: postscript (link)
11. 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, S2CID 14878976.
12. Tabur, V.; Bedding, T. R. (2009), "Long-term photometry and periods for 261 nearby pulsating M giants", Monthly Notices of the Royal Astronomical Society, 400 (4): 1945–61, arXiv:0908.3228, Bibcode:2009MNRAS.400.1945T, doi:10.1111/j.1365-2966.2009.15588.x, S2CID 15358380.
13. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22