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Eta Circini, HD132905, HIP73776, HR5593

Eta Circini is a white to yellow star that can be located in the constellation of Circinus. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Eta Circini is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR5593. HIP73776 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD132905.

Location of Eta Circini

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 Eta Circini, the location is 15h 04m 48.05 and -64d 01` 52.9 .

Proper Motion of Eta Circini

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 9.35 ± 0.18 miliarcseconds/year towards the north and 102.65 ± 0.30 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is 44.80000 km/s with an error of about 0.80 km/s .

Eta Circini 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 113.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

Physical Properties (Colour, Temperature, Radius) of Eta Circini

Eta Circini has a spectral type of G8III. This means the star is a white to yellow star. The star is 7339.00000000 Parsecs from the Galactic Centre or terms of Light Years is 23937.1278161600000000s. The star has a B-V Colour Index of 0.93 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,989 Kelvin.

Eta Circini Radius has been calculated as being 9.53 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 6,627,580.78.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 9.84. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Eta Circini Apparent and Absolute Magnitudes

Eta Circini has an apparent magnitude of 5.16 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 0.59 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.52. 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 Eta Circini

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 12.20 which gave the calculated distance to Eta Circini as 267.35 light years away from Earth or 81.97 parsecs. It would take a spaceship travelling at the speed of light, 267.35 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 11.82 which put Eta Circini at a distance of 275.94 light years or 84.60 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 7,339.00 Parsecs or 23,937.13 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

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.

Eta Circini Facts

Alternative Names

Bayer DesignationEta Circini
Hipparcos Library I.D.73776
Yale Bright Star Catalogue (HR) Id5593
Henry Draper Designation132905

Visual Facts

Star Type star
Absolute Magnitude0.59 / 0.52
Visual / Apparent Magnitude5.16
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)15h 04m 48.05
Declination (Dec.)-64d 01` 52.9
Galactic Latitude-4.84 degrees
Galactic Longitude316.91 degrees
1997 Distance from Earth12.20 Parallax (milliarcseconds)
 267.35 Light Years
 81.97 Parsecs
2007 Revised Distance from Earth11.82 Parallax (milliarcseconds)
 275.94 Light Years
 84.60 Parsecs
Galacto-Centric Distance23,937.13 Light Years / 7,339.00 Parsecs
Proper Motion Dec.9.35 ± 0.18 milliarcseconds/year
Proper Motion RA.102.65 ± 0.30 milliarcseconds/year
B-V Index0.93
Radial Velocity44.80 ± 0.80 km/s
Spectral TypeG8III
Colour(G) White to Yellow

Estimated Facts

Luminosity (x the Sun)113.0000000
Calculated Effective Temperature4,989 Kelvin

Sources and Links

SIMBAD SourceLink

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