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Eta Cancri, 33 Cancri, HD72292, HIP41909

Eta Cancri is a orange to red giant star that can be located in the constellation of Cancer. Eta Cancri is the brightest star in Cancer 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 Cancri is the Bayer Classification for the star. HIP41909 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD72292.

Location of Eta Cancri

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 Cancri, the location is 08h 32m 42.52 and +20d26`28.6 .

Proper Motion of Eta Cancri

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 -44.31 ± 0.21 miliarcseconds/year towards the north and -46.33 ± 0.40 miliarcseconds/year east if we saw them in the horizon.

Eta Cancri 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 58.0000000 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 Cancri

Eta Cancri has a spectral type of K3III. This means the star is a orange to red giant star. The star is 7472.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24370.9250636800000000s. The star has a B-V Colour Index of 1.25 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,405 Kelvin.

Eta Cancri Radius has been calculated as being 13.15 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 9,151,489.45.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 12.62. 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 0.11 with an error value of 0.06 Fe/H with the Sun has a value of 1 to put it into context.

Eta Cancri Apparent and Absolute Magnitudes

Eta Cancri has an apparent magnitude of 5.33 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 0.43 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 Cancri

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 10.46 which gave the calculated distance to Eta Cancri as 311.82 light years away from Earth or 95.60 parsecs. It would take a spaceship travelling at the speed of light, 311.82 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 10.93 which put Eta Cancri at a distance of 298.41 light years or 91.49 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 7,472.00 Parsecs or 24,370.93 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 Cancri Facts

Alternative Names

Flamsteed Name33 Cancri
Flamsteed Short Name33 Cnc
Bayer DesignationEta Cancri
Hipparcos Library I.D.41909
Bonner DurchmusterungBD+20 2109
Henry Draper Designation72292

Visual Facts

Star Typegiant star
Absolute Magnitude0.43 / 0.52
Visual / Apparent Magnitude5.33
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)08h 32m 42.52
Declination (Dec.)+20d26`28.6
Galactic Latitude31.06 degrees
Galactic Longitude204.33 degrees
1997 Distance from Earth10.46 Parallax (milliarcseconds)
 311.82 Light Years
 95.60 Parsecs
2007 Revised Distance from Earth10.93 Parallax (milliarcseconds)
 298.41 Light Years
 91.49 Parsecs
Galacto-Centric Distance24,370.93 Light Years / 7,472.00 Parsecs
Proper Motion Dec.-44.31 ± 0.21 milliarcseconds/year
Proper Motion RA.-46.33 ± 0.40 milliarcseconds/year
B-V Index1.25
Radial Velocity22.46 ± 0.19 km/s
Iron Abundance0.11 ± 0.06 Fe/H
Spectral TypeK3III
Colour(K) Orange to Red

Estimated Facts

Luminosity (x the Sun)58.0000000
Calculated Effective Temperature4,405 Kelvin

Sources and Links

SIMBAD SourceLink

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