Universe Guide

Ran (Epsilon Eridani, 18 Eridani) Star Facts

Ran Facts

  • Ran is a main sequence star that can be located in the constellation of Eridanus. The description is based on the spectral class.
  • Ran is a main star of the constellation outline.
  • Based on the spectral type (K2V) of the star, the star's colour is orange to red .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • Ran has at least 1 Extrasolar Planets believed to be in orbit around the star.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 10.49 light years away from us. Distance

Information on Ran

Whilst Sadira is referenced as being a name for Epsilon Eridani on the net, it would seem its not accepted by the powers that be at IAU which named it Ran, after a Norse God. Ran was a sea Goddess who stirred up the waves and captured sailors with her net. Epsilon Eridani b was named AEgir which is the name of Ran`s husband.

The star is well known for having a number of planets as well as an asteroid belt. The star is relatively close to us compared to other stars in the milky way

Ran's Alternative Names

Epsilon Eridani (Eps Eri) 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 HR1084. HIP16537 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD22049. The Gliese ID of the star is GL 144. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

Ran has alternative name(s) :- Sadira.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John named the stars in the constellation with a number and its latin name, this star's Flamsteed designation is 18 Eridani. The Flamsteed name can be shortened to 18 Eri.

The Gould star designation is one that was designed by American astronomer, Benjamin Apthorp Gould. Gould stars are predominantly in the Southern and Equatorial constellations but do appear in northern constellations such as Bootes and Orion. The star has the designation 101 G. Eridani. There are no stars with a Gould designation in Ursa Major for example.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD-09 697.

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

Location of Ran

The location of the main sequence 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 Ran, the location is 03h 32m 56.42 and -09° 27` 29.9 .

Radial Velocity and Proper Motion of Ran

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 19.49 ± 0.11 milliarcseconds/year towards the north and -975.17 ± 0.16 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 16.43000 km/s with an error of about 0.09 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.

Physical Properties of Ran

Ran Temperature and Colour

Based on the star's spectral type of K2V , Ran's colour and type is orange to red main sequence star. The star's effective temperature is 5,146 Kelvin which is cooler than our own Sun's effective Temperature which is 5,777 Kelvin

Ran 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 0.37 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Ran Radius

Ran estimated radius has been calculated as being 0.70 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 484,025.59.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 0.6956389562614836830872616454. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

Ran Iron Abundance

Ran Iron Abundance is -0.06 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context. The value comes from the Hipparcos Extended Catalog.

Ran Apparent and Absolute Magnitudes

Ran has an apparent magnitude of 3.72 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 6.18 If you used the 2007 Parallax value, you would get an absolute magnitude of 6.18. 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 Ran

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 310.75000 which gave the calculated distance to Ran as 10.50 light years away from Earth or 3.22 parsecs. If you want that in miles, it is about 61,725,566,418,427.91, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 310.94000 which put Ran at a distance of 10.49 light years or 3.22 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 664,168.05 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 7,402.00 Parsecs or 24,142.61 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 Ran

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 A3807369,558,109.29
Speed of Sound (Mach 1)767.2699,168,581.60
Concorde (Mach 2)1,534.544,584,284.83
New Horizons Probe33,000213,174.80
Speed of Light670,616,629.0010.49

Meteor Showers Radiating from near Ran

The November epsilon Eridanids Meteor Shower radiants from a point near this star. The meteor shower runs typically between with a peak date of 23rd November. The speed of a meteor in the shower is 11 Km/s.

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 Ran Facts and Figures

Visual Facts

Primary / Proper / Traditional NameRan
Alternative NamesEpsilon Eridani, Eps Eri, Sadira, HD 22049, HIP 16537, HR 1084, 101 G. Eridani, 18 Eridani, 18 Eri, BD-09 697, Gliese 144
Spectral TypeK2V
Constellation's Main StarYes
Multiple Star SystemYes
Star Type Main Sequence Dwarf Star
ColourOrange to Red
GalaxyMilky Way
Absolute Magnitude 6.18 / 6.18
Visual / Apparent Magnitude3.72
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)03h 32m 56.42
Declination (Dec.)-09° 27` 29.9
Galactic Latitude-48.04927945 degrees
Galactic Longitude195.84649077 degrees
1997 Distance from Earth310.75000 Parallax (milliarcseconds)
  10.50 Light Years
 3.22 Parsecs
2007 Distance from Earth310.94000 Parallax (milliarcseconds)
 10.49 Light Years
 3.22 Parsecs
 664,168.05 Astronomical Units
Galacto-Centric Distance24,142.61 Light Years / 7,402.00 Parsecs
Proper Motion Dec.19.49000 ± 0.11000 milliarcseconds/year
Proper Motion RA.-975.17000 ± 0.16000 milliarcseconds/year
B-V Index0.88
Radial Velocity16.43000 ± 0.09 km/s
Iron Abundance-0.0600 ± 9.99 Fe/H
Semi-Major Axis9283.0000000
Stellar Luminosity (Lsun)0.3700000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count1

Estimated Calculated Facts

Radius (x the Sun)0.70
Effective Temperature5,096 Kelvin

Sources and Links

SIMBAD SourceLink

Location of Ran in Eridanus

Ran Location in Eridanus

The map was generated using Night Vision, an awesome free application by Brian Simpson.

List of Extrasolar Planets orbiting Ran

NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastronInclination
eps Eridani bConfirmed0.22692.0000.0720003.39180.00089.000

Eridanus Main Stars

Ran Solar System

This is a N.A.S.A. impression of what the solar system might look like. If the star is not on display, its because its so small compared to the orbits of the outer planets. The green area denotes the habital zone which if the planet is within that area, life could exist. The habital zone might not appear on the picture because its outside the area for the picture. Our planets show the orbit of the planet if its was in our solar system. For more information about the planet and other exoplanetary stuff, visit N.A.S.A.

Ran Solar System

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