Universe Guide


45 G. Eri - HD18557 - HIP13883

45 G. Eri is a blue star that can be located in the constellation of Eridanus. HIP13883 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD18557. The Id of the star in the Gould Star Catalogue is 45. Stars in the southern hemisphere are more likely to have a Gould Id than the northern hemisphere. For example, there are no Gould classified stars in Ursa Major.

Location of 45 G. Eri

The location of the star in the galaxy 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 star is compared to the celestial equator and is expressed in degrees. For 45 G. Eri, the location is 02h 58m 47.31 and -09d46`35.3 .

Proper Motion of 45 G. Eri

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 -015.47 ± 000.28 towards the north and -008.62 ± 000.41 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 45 G. Eri

45 G. Eri has a spectral type of A2m. This means the star is a blue star. The star has a B-V Colour Index of 0.22 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,253 Kelvin.

45 G. Eri has been calculated as 3.15 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,189,470.13.km.

45 G. Eri Apparent and Absolute Magnitudes

45 G. Eri has an apparent magnitude of 6.14 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 1.37 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.37. 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 45 G. Eri

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 11.11 which gave the calculated distance to 45 G. Eri as 293.58 light years away from Earth or 90.01 parsecs. It would take a spaceship travelling at the speed of light, 293.58 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

In 2007, Hipparcos data was revised with a new parallax of 11.10 which put 45 G. Eri at a distance of 293.84 light years or 90.09 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.

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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

45 G. Eri Facts

Alternative Names

Traditional Name45 G. Eri
Hipparcos Library I.D.13883
Bonner DurchmusterungBD-10 585
Gould I.D.45
Henry Draper Designation18557

Visual Facts

Star Type star
Absolute Magnitude1.37 / 1.37
Apparent Magnitude6.14
Right Ascension (R.A.)02h 58m 47.31
Declination (Dec.)-09d46`35.3
1997 Distance from Earth11.11 Parallax (milliarcseconds)
 293.58 Light Years
 90.01 Parsecs
2007 Revised Distance from Earth11.10 Parallax (milliarcseconds)
 293.84 Light Years
 90.09 Parsecs
Proper Motion Dec.-15.47 ± 0.28 milliarcseconds/year
Proper Motion RA.-8.62 ± 0.41 milliarcseconds/year
B-V Index0.22
Spectral TypeA2m
Colour(A) blue

Estimated Facts

Radius (x the Sun)3.15
Calculated Effective Temperature7,253 Kelvin

Sources and Links

SIMBAD SourceLink

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