Rho Indi

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ρ Indi
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Indus
Right ascension 22h 54m 39.482s [1]
Declination –70° 04 25.35 [1]
Apparent magnitude  (V)+6.05 [2]
Characteristics
Spectral type G1 V Fe+0.3 [3]
U−B color index +0.22 [4]
B−V color index +0.66 [4]
Astrometry
Radial velocity (Rv)−2.29±0.12 [1]  km/s
Proper motion (μ)RA: −43.140 [1]   mas/yr
Dec.: +72.728 [1]   mas/yr
Parallax (π)37.4641 ± 0.0253  mas [1]
Distance 87.06 ± 0.06  ly
(26.69 ± 0.02  pc)
Absolute magnitude  (MV)+3.90 [5]
Details [6]
Mass 1.317±0.083  M
Radius 1.456±0.024  R
Luminosity 2.24  L
Surface gravity (log g)4.23  cgs
Temperature 5,849  K
Metallicity [Fe/H]0.18  dex
Rotation 26.7  d [7]
Rotational velocity (v sin i)3.1 km/s
Age 4.6+1.0
−0.4
  Gyr
Other designations
ρ Ind, CPD–70°2971, FK5 865, HR 8701, HD  216437, HIP 113137, SAO 258084.
Database references
SIMBAD data
Exoplanet Archive data
Extrasolar Planets
Encyclopaedia
data

ρ Indi, Latinised as Rho Indi (also HR 8701 or HD 216437), is a yellow-hued star in the constellation Indus. With an apparent visual magnitude of +6.05 [2] it is, barely, a naked eye star, not visible in the northern hemisphere outside the tropics. Based upon an annual parallax shift of 37.46  mas, it is located 87 light-years (27 parsecs ) from the Sun. The star is moving closer to the Sun with a radial velocity of −2 km/s. [1]

Contents

Properties

The stellar classification of Rho Indi is G1 V Fe+0.3, [3] which indicates it is a G-type main-sequence star with a mild overabundance of iron in its outer atmosphere. However, Houk and Cowley (1975) classified it as G2.5 IV, [8] suggesting it is instead a somewhat more evolved subgiant star. It has an estimated 1.32 times the mass of the Sun and 1.46 times the Sun's radius. The star is radiating about 2.24 times the Sun's luminosity from its photosphere at an effective temperature of 5,849 K. It is around 4.6 billion years old and is spinning with a leisurely projected rotational velocity of 3.1 km/s. [6]

Planetary system

On September 17, 2002, this star was found to have a planetary companion, designated Rho Indi b. [9] The discovery was made by measuring variations in the host star's radial velocity, thereby indicating the presence of a perturbing object. Based upon the data, the object is orbiting the host star with a period of about 3.7 years at an eccentricity of 0.32. The semimajor axis for this orbit is around 2.5 times the distance from the Earth to the Sun. Since the inclination of the orbit to the line-of-sight was initially unknown, only a lower bound on the planet's mass could be determined. It has at least 2.3 times Jupiter's mass. [9] In 2023, the inclination and true mass of Rho Indi b were determined via astrometry. [10]

The Rho Indi planetary system [10]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(years)
Eccentricity Inclination Radius
b 3.88±0.73  MJ 2.501+0.036
−0.037
3.658±0.0340.318±0.02835.0+10.0
−6.1
or 145.0+6.1
−10.0
°

See also

Related Research Articles

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References

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