Delta Indi

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Delta Indi
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Indus
Right ascension 21h 57m 55.07353s[1]
Declination −54° 59′ 33.2740″[1]
Apparent magnitude (V) +4.40[2] (4.80 + 5.96)[3]
Spectral type F0 IV + F0 IV[4]
U−B color index +0.10[2]
B−V color index +0.28[2]
Proper motion (μ) RA: +41.94[1] mas/yr
Dec.: −3.93[1] mas/yr
Parallax (π) 17.34 ± 0.48[1] mas
Distance 188 ± 5 ly
(58 ± 2 pc)
Absolute magnitude (MV) +0.60[5]
Period (P) 12.237±0.080 yr
Semi-major axis (a) 0.176±0.004
Eccentricity (e) 0.032±0.032
Inclination (i) 76.3±2.0°
Longitude of the node (Ω) 90.8±2.0°
Periastron epoch (T) 2007.518±0.480
Argument of periastron (ω)
δ Ind A
Mass 1.78±0.21[4] M
Luminosity 48[5] L
Surface gravity (log g) 3.85[6] cgs
Temperature 7,445±253[6] K
Metallicity [Fe/H] −0.21[5] dex
Rotational velocity (v sin i) 130[7] km/s
Age 462[6] Myr
δ Ind B
Mass 1.33±0.16[4] M
Other designations
δ Ind, CPD−55° 9733, FK5 824, HD 208450, HIP 108431, HR 8368, SAO 247244, WDS J21579-5500AB[8]
Database references

Delta Indi, Latinized from δ Indi, is a binary star[4] system in the southern constellation of Indus. It is visible to the naked eye with a combined apparent visual magnitude of +4.40.[2] The brighter primary, designated component A, is magnitude 4.80 while the companion, component B, is magnitude 5.96.[3] Based upon an annual parallax shift of 14.07 mas as measured from Earth,[1] the system is located about 188 light years from the Sun.

The binary nature of this system was discovered by South African astronomer William Stephen Finsen from 1936 onward,[4] with his published orbital elements appearing in 1956.[9] The pair have an orbital period of 12.2 years, a semimajor axis of 0.176 arc seconds, and an eccentricity of around 0.03. Both components have been listed with a stellar classification of F0 IV by multiple authors, suggesting they are yellow-white hued F-type subgiant stars. However, their estimated masses don't match this classification, so Docobo and Andrade (2013) suggest the Hipparcos parallax may have been underestimated.[4]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d 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. 
  3. ^ a b Malkov, O. Yu.; et al. (2012), "Dynamical Masses of a Selected Sample of Orbital Binaries", Astronomy & Astrophysics, 546: 5, Bibcode:2012A&A...546A..69M, doi:10.1051/0004-6361/201219774, A69. 
  4. ^ a b c d e f g Docobo, J. A.; Andrade, M. (2013), "Dynamical and physical properties of 22 binaries discovered by W. S. Finsen", Monthly Notices of the Royal Astronomical Society, 428 (1): 321–339, Bibcode:2013MNRAS.428..321D, doi:10.1093/mnras/sts045. 
  5. ^ a b c Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971Freely accessible, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. 
  6. ^ a b c 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, arXiv:1501.03154Freely accessible, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146. 
  7. ^ van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572Freely accessible, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2. 
  8. ^ "del Ind". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-18. 
  9. ^ Finsen, W. S. (1956), "The Orbit of Phi 312 = Delta Indi", Monthly Notes of the Astronomical Society of South Africa, 15: 49, Bibcode:1956MNSSA..15...49F.