Delta Indi

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]
Characteristics
Spectral type F0 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)17.34 ± 0.48 mas[1]
Distance188 ± 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
Mass1.78±0.21[4] M☉
Luminosity48[5] L☉
Surface gravity (log g)3.85[6] cgs
Temperature7,445±253[6] K
Metallicity [Fe/H]−0.21[5] dex
Rotational velocity (v sin i)130[7] km/s
Age462[6] Myr
δ Ind B
Mass1.33±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
SIMBADdata

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. 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 Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Nicolet1978 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Malkov2012 was invoked but never defined (see the help page).
  4. ^ a b c d e f g Cite error: The named reference Docobo2013 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference David2015 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference vanBelle2012 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Finsen1956 was invoked but never defined (see the help page).