Universe Guide

FI Eridani

FI Eridani Facts

  • FI Eridani is a pulsating subgiant star that can be located in the constellation of Eridanus. The description is based on the spectral class.
  • FI Eridani is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (F0IV) of the star, the star's colour is yellow to white .
  • The star can not be seen by the naked eye, you need a telescope to see it.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 956.49 light years away from us. Distance

FI Eridani's Alternative Names

HIP12373 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD16698.

FI Eridani has alternative name(s) :- FI Eri, FI Eri.

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

Location of FI Eridani

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 FI Eridani, the location is 02h 39m 17.03 and -43° 48` 05.7 .

Proper Motion of FI Eridani

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 -18.93 ± 0.60 milliarcseconds/year towards the north and 16.10 ± 0.78 milliarcseconds/year east if we saw them in the horizon. . 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 FI Eridani

FI Eridani Temperature and Colour

Based on the star's spectral type of F0IV , FI Eridani's colour and type is yellow to white subgiant star. The star has a B-V Colour Index of 0.31 which means the star's temperature is about 7,167 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

FI Eridani Radius

FI Eridani estimated radius has been calculated as being 3.05 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,121,770.43.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 3.62. 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.

FI Eridani Apparent and Absolute Magnitudes

FI Eridani has an apparent magnitude of 8.46 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 1.49 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.12. 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 FI Eridani

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 4.03 which gave the calculated distance to FI Eridani as 809.34 light years away from Earth or 248.14 parsecs. If you want that in miles, it is about 4,757,806,659,532,422.92, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 3.41 which put FI Eridani at a distance of 956.49 light years or 293.26 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 60,488,795.59 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.

Travel Time to FI 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 A380736871,519,156.89
Speed of Sound (Mach 1)767.269836,001,584.15
Concorde (Mach 2)1,534.54418,000,247.29
New Horizons Probe33,00019,437,518.17
Speed of Light670,616,629.00956.49

Variable Type of FI Eridani

The star is a pulsating Delta Scuti variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. FI Eridani brightness ranges from a magnitude of 8.588 to a magnitude of 8.499 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.2 days (variability).

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.

Hide Explanations
Show GridLines

Additional FI Eridani Facts and Figures

Visual Facts

Primary / Proper / Traditional NameFI Eridani
Alternative NamesFI Eri, HD 16698, HIP 12373, FI Eri
Spectral TypeF0IV
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeSubgiant Star
ColourYellow - White
GalaxyMilky Way
Absolute Magnitude 1.49 / 1.12
Visual / Apparent Magnitude8.46
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)02h 39m 17.03
Declination (Dec.)-43° 48` 05.7
Galactic Latitude-62.64 degrees
Galactic Longitude257.53 degrees
1997 Distance from Earth4.03 Parallax (milliarcseconds)
 809.34 Light Years
 248.14 Parsecs
2007 Distance from Earth3.41 Parallax (milliarcseconds)
 956.49 Light Years
 293.26 Parsecs
 60,488,795.59 Astronomical Units
Proper Motion Dec.-18.93 ± 0.60 milliarcseconds/year
Proper Motion RA.16.10 ± 0.78 milliarcseconds/year
B-V Index0.31

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeDelta Scuti
Mean Variability Period in Days0.171
Variable Magnitude Range (Brighter - Dimmer)8.499 - 8.588

Estimated Calculated Facts

Radius (x the Sun)3.62
Effective Temperature7,167 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Comments and Questions

There's no register feature and no need to give an email address if you don't need to. All messages will be reviewed before being displayed. Comments may be merged or altered slightly such as if an email address is given in the main body of the comment.

You can decline to give a name which if that is the case, the comment will be attributed to a random star. A name is preferred even if its a random made up one by yourself.

This website is using cookies. More info. That's Fine