Universe Guide

G Eridani

G Eridani Facts

  • G Eridani is a giant star that can be located in the constellation of Eridanus. The description is based on the spectral class.
  • G Eridani is a main star of the constellation outline.
  • Based on the spectral type (G8III) of the star, the star's colour is yellow .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • The star is calculated at being about 209.89 light years away from us. Distance

G Eridani's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR1195. HIP17874 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD24160.

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 138 G. Eridani. There are no stars with a Gould designation in Ursa Major for example.

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

Location of G Eridani

The location of the giant 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 G Eridani, the location is 03h 49m 27.28 and -36° 12` 00.4 .

Radial Velocity and Proper Motion of G Eridani

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 -57.01 ± 0.13 milliarcseconds/year towards the north and -49.18 ± 0.17 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 2.00000 km/s with an error of about 0.70 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 G Eridani

G Eridani Colour and Temperature

Based on the star's spectral type of G8III , G Eridani's colour and type is yellow giant star. The star has a B-V Colour Index of 0.92 which means the star's temperature is about 5,010 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

G Eridani 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 100.59 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

G Eridani Radius

G Eridani estimated radius has been calculated as being 11.67 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 8,122,899.92.km. If you need the diameter of the star, you just need to multiple the radius by 2. 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.

G Eridani Apparent and Absolute Magnitudes

G Eridani has an apparent magnitude of 4.17 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. Using the supplied Parallax value, you would get an absolute magnitude of 0.13 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 G Eridani

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 15.54000 which gave the calculated distance to G Eridani as 209.89 light years away from Earth or 64.35 parsecs. If you want that in miles, it is about 1,233,864,679,577,507.90, based on 1 Ly = 5,878,625,373,183.61 miles.

The star's Galacto-Centric Distance is 7,422.00 Parsecs or 24,207.84 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 G Eridani

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 A380736191,244,190.57
Speed of Sound (Mach 1)767.269183,450,294.83
Concorde (Mach 2)1,534.5491,725,027.87
New Horizons Probe33,0004,265,324.98
Speed of Light670,616,629.00209.89

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 G Eridani Facts and Figures

Visual Facts

Primary / Proper / Traditional NameG Eridani
Alternative NamesG Eri, HD 24160, HIP 17874, HR 1195, 138 G. Eridani
Spectral TypeG8III
Constellation's Main StarYes
Multiple Star SystemNo / Unknown
Star TypeGiant Star
GalaxyMilky Way
Absolute Magnitude 0.13
Visual / Apparent Magnitude4.17
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)03h 49m 27.28
Declination (Dec.)-36° 12` 00.4
Galactic Latitude-51.39955203 degrees
Galactic Longitude237.88521050 degrees
Distance from Earth15.54000 Parallax (milliarcseconds)
 209.89 Light Years
 64.35 Parsecs
 13,273,047.79 Astronomical Units
Galacto-Centric Distance24,207.84 Light Years / 7,422.00 Parsecs
Proper Motion Dec.-57.01000 ± 0.13000 milliarcseconds/year
Proper Motion RA.-49.18000 ± 0.17000 milliarcseconds/year
B-V Index0.92
Radial Velocity2.00000 ± 0.70 km/s
Semi-Major Axis8773.0000000
Stellar Luminosity (Lsun)100.5900000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Estimated Calculated Facts

Radius (x the Sun)11.67
Effective Temperature5,010 Kelvin

Sources and Links

SIMBAD SourceLink

Eridanus Main Stars

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