Delta Indi
Location of δ Indi (circled in red) | |
| 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] |
| Characteristics | |
| Spectral type | 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) | 17.34±0.48 mas[1] |
| Distance | 188 ± 5 ly (58 ± 2 pc) |
| Absolute magnitude (MV) | +0.60[5] |
| Orbit[4] | |
| 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) (secondary) | 64.9±11.0° |
| Details | |
| 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 | |
| SIMBAD | data |
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 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,[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. 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 don't match this classification, so Docobo and Andrade (2013) suggest the Hipparcos parallax may have been underestimated.[4] One paper has published separate spectral classes of A8(V) and F3(V) respectively for the two components.[10]
References
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