Universe Guide

Rho Indi

Rho Indi Facts

Rho Indi's Alternative Names

Rho Indi (Rho Ind) is the Bayer Classification for the star. The Bayer Classification was created by Johann Bayer in 1603. The brightest star in the constellation is normally given the Alpha designation, there are exceptions such as Pollux which is Beta Geminorum.

The Id of the star in the Yale Bright Star Catalogue is HR8701. HIP113137 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD216437.

More details on objects' alternative names can be found at Star Names .

Location of Rho Indi

The location of the subgiant star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the object is compared to the celestial equator and is expressed in degrees. For Rho Indi, the location is 22h 54m 39.56 and -70° 04` 26.0 .

Radial Velocity and Proper Motion of Rho Indi

Proper Motion

All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving 73.04 ± 0.26 milliarcseconds/year towards the north and -43.89 ± 0.36 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -4.00 km/s with an error of about 0.92 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Rho Indi Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 2.57 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature, Metallicity, Age, Mass) of Rho Indi

Rho Indi Colour and Temperature

Rho Indi has a spectral type of G4IV-V. This means the star is a yellow subgiant star.

The star's effective temperature is 5,849 Kelvin which is hotter than our own Sun's effective Temperature which is 5,777 Kelvin.

Rho Indi Radius

Radius has been calculated as being 1.58 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,099,708.24.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 1.60. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's solar mass is 1.06 times that of the Sun's. The Sun's Mass is 1,989,100,000,000,000,000,000 billion kg. which to calculate using this website is too large. To give idea of size, the Sun is 99.86% the mass of the solar system.

The star's metallicity is 0.250000, this value is the fractional amount of the star that is not Hydrogen (X) or Helium (Y). An older star would have a high metallicity whereas a new star would have a lower one.

The stars age according to Hipparcos data files put the star at an age of about 7.80 Billion years old but could be between 7.00 and 8.70 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

Rho Indi Apparent and Absolute Magnitudes

Rho Indi has an apparent magnitude of 6.04 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of 3.92 If you used the 2007 Parallax value, you would get an absolute magnitude of 3.90. Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to Rho Indi

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 37.71 which gave the calculated distance to Rho Indi as 86.49 light years away from Earth or 26.52 parsecs. If you want that in miles, it is 58,001,632,242.

In 2007, Hipparcos data was revised with a new parallax of 37.39 which put Rho Indi at a distance of 87.23 light years or 26.75 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.

Using the 2007 distance, the star is roughly 5,517,545.12 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.

The star's Galacto-Centric Distance is 7,386.00 Parsecs or 24,090.42 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Rho Indi

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A38073679,480,826.83
Speed of Sound (Mach 1)767.26976,241,694.30
Concorde (Mach 2)1,534.5438,120,797.47
New Horizons Probe33,0001,772,663.29
Speed of Light670,616,629.0087.23

Source of Information

The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

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Additional Rho Indi Facts and Figures

Visual Facts

Primary / Proper / Traditional NameRho Indi
Alternative NamesRho Ind, HD 216437, HIP 113137, HR 8701
Spectral TypeG4IV-V
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeSubgiant Star
GalaxyMilky Way
Age 7.80 Billion Years Old
Age Range7.00 - 8.70 Billion Years Old
Absolute Magnitude 3.92 / 3.90
Visual / Apparent Magnitude6.04
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)22h 54m 39.56
Declination (Dec.)-70° 04` 26.0
Galactic Latitude-43.91 degrees
Galactic Longitude316.27 degrees
1997 Distance from Earth37.71 Parallax (milliarcseconds)
 86.49 Light Years
 26.52 Parsecs
2007 Distance from Earth37.39 Parallax (milliarcseconds)
 87.23 Light Years
 26.75 Parsecs
 5,517,545.12 Astronomical Units
Galacto-Centric Distance24,090.42 Light Years / 7,386.00 Parsecs
Proper Motion Dec.73.04 ± 0.26 milliarcseconds/year
Proper Motion RA.-43.89 ± 0.36 milliarcseconds/year
B-V Index0.66
Radial Velocity-4.00 ± 0.92 km/s
Iron Abundance0.21 ± 0.01 Fe/H
Semi-Major Axis9665.00
Stellar Luminosity (Lsun)2.57

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count1

Estimated Calculated Facts

Radius (x the Sun)1.60
Effective Temperature5,689 Kelvin
Mass Compared to the Sun1.06

Sources and Links

SIMBAD SourceLink

List of Extrasolar Planets orbiting Rho Indi

NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
HD 216437 bConfirmed1256.0000.2920022.3263.000

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