Astronomy:Delta Indi
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| Observation data 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] |
| Characteristics | |
| Spectral type | A5 IV + F0 IV[4] |
| U−B color index | +0.10[2] |
| B−V color index | +0.28[2] |
| Astrometry | |
| Proper motion (μ) | RA: +41.94[1] mas/yr Dec.: −3.93[1] mas/yr |
| Parallax (π) | 21.77 ± 0.34[4] mas |
| Distance | 150 ± 2 ly (45.9 ± 0.7 pc) |
| Absolute magnitude (MV) | +0.60[5] |
| Orbit[4] | |
| Period (P) | 12.156±0.090 yr |
| Semi-major axis (a) | 0.173±0.002″ |
| Eccentricity (e) | 0.005±0.003 |
| Inclination (i) | 75.2±0.5° |
| Longitude of the node (Ω) | 95.0±0.5° |
| Periastron epoch (T) | B 2030.764±1.205 |
| Argument of periastron (ω) (secondary) | 34.2±10.8° |
| Details | |
| δ Ind A | |
| Mass | 1.83±0.04[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 | 1.57±0.04[4] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
Delta Indi, Latinized from δ Indi, is a binary star[9] 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 17.34 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,[9] with his published orbital elements appearing in 1956.[10] The pair have an orbital period of 12.16 years, a semimajor axis of 0.173 arc seconds, and an eccentricity of around 0.005.[4] They 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 do not match this classification, so Docobo and Andrade (2013) suggest the Hipparcos parallax may have been underestimated.[9] One paper has published separate spectral classes of A8(V) and F3(V) respectively for the two components.[11] A more recent publication suggests spectral types of A5IV + F0IV.[4]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 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.
- ↑ 2.0 2.1 2.2 2.3 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.
- ↑ 3.0 3.1 Malkov, O. Yu. et al. (2012), "Dynamical Masses of a Selected Sample of Orbital Binaries", Astronomy & Astrophysics 546: 5, doi:10.1051/0004-6361/201219774, A69, Bibcode: 2012A&A...546A..69M.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Docobo, José Ángel; Campo, Pedro Pablo; Gómez, Jorge; Piccotti, Luca; Caballero-Valdes, Camila; Mendez, Rene A.; Costa, Edgardo (2026-07-31), "22 Orbits of Binaries Based on SOAR Speckle Observations: Systems with Early Type Components", The Astronomical Journal 172 (2): 133, doi:10.3847/1538-3881/ae877f, ISSN 0004-6256.
- ↑ 5.0 5.1 5.2 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 6.0 6.1 6.2 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, doi:10.1088/0004-637X/804/2/146, Bibcode: 2015ApJ...804..146D.
- ↑ van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review 20 (1), doi:10.1007/s00159-012-0051-2, Bibcode: 2012A&ARv..20...51V.
- ↑ "del Ind". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=del+Ind.
- ↑ 9.0 9.1 9.2 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, doi:10.1093/mnras/sts045, Bibcode: 2013MNRAS.428..321D, http://mnras.oxfordjournals.org/content/428/1/321.full.
- ↑ 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.
- ↑ Beavers, W. I.; Cook, D. B. (1980), "Scanner studies of composite spectra I. Dwarfs.", The Astrophysical Journal Supplement Series 44: 489, doi:10.1086/190702, Bibcode: 1980ApJS...44..489B.
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