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Azha, Eta Eridani, 3 Eridani, HD18322, HIP13701, HR874

Azha (Eta Eridani) is a orange to red subgiant star that can be located in the constellation of Eridanus. Azha is the brightest star in Eridanus based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Eta Eridani is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR874. HIP13701 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD18322. The Id of the star in the Gould Star Catalogue is 39. 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 Azha

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 Azha, the location is 02h 56m 25.60 and -08d 53` 51.4 .

Proper Motion of Azha

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 -220.16 ± 0.12 miliarcseconds/year towards the north and 77.36 ± 0.19 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Azha

Azha has a spectral type of K1III-IV. This means the star is a orange to red subgiant star. The star is 7424.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24214.3666585600000000s. The star has a B-V Colour Index of 1.08 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,700 Kelvin.

Azha Radius has been calculated as being 9.57 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 6,655,548.73.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 9.83. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is -0.08 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Azha Apparent and Absolute Magnitudes

Azha has an apparent magnitude of 3.89 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 0.84 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.78. 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 Azha

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 24.49 which gave the calculated distance to Azha as 133.18 light years away from Earth or 40.83 parsecs. It would take a spaceship travelling at the speed of light, 133.18 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 23.89 which put Azha at a distance of 136.53 light years or 41.86 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.

The star's Galacto-Centric Distance is 7,424.00 Parsecs or 24,214.37 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Meteor Showers Radiating from near Azha

The Eta Eridanids Meteor Shower radiants from a point near this star. The meteor shower runs typically between 3 Aug- 14 Aug with a peak date of 09-Aug. The speed of a meteor in the shower is 65 Km/s. The amount of meteors predicted to be seen per hour (Zenith Hourly Rate) is 65.

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.

Azha Facts

Alternative Names

Traditional/Proper NameAzha
Flamsteed Name3 Eridani
Flamsteed Short Name3 Eri
Bayer DesignationEta Eridani
Hipparcos Library I.D.13701
Yale Bright Star Catalogue (HR) Id874
Bonner DurchmusterungBD-09 553
Gould I.D.39
Henry Draper Designation18322

Visual Facts

Star Typesubgiant star
Absolute Magnitude0.84 / 0.78
Visual / Apparent Magnitude3.89
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)02h 56m 25.60
Declination (Dec.)-08d 53` 51.4
Galactic Latitude-55.31 degrees
Galactic Longitude187.15 degrees
1997 Distance from Earth24.49 Parallax (milliarcseconds)
 133.18 Light Years
 40.83 Parsecs
2007 Revised Distance from Earth23.89 Parallax (milliarcseconds)
 136.53 Light Years
 41.86 Parsecs
Galacto-Centric Distance24,214.37 Light Years / 7,424.00 Parsecs
Proper Motion Dec.-220.16 ± 0.12 milliarcseconds/year
Proper Motion RA.77.36 ± 0.19 milliarcseconds/year
B-V Index1.08
Radial Velocity-20.30 ± 0.70 km/s
Iron Abundance-0.08 ± 9.99 Fe/H
Spectral TypeK1III-IV
Colour(K) Orange to Red

Estimated Facts

Calculated Effective Temperature4,700 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Location of Azha in Eridanus

Azha (Eta Eridani) Location in Eridanus

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

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