Universe Guide


Iota Cancri B, Iota Cancri A, 48 Cancri, HD74738, HIP43100

Iota Cancri B (Iota Cancri A) is a white to yellow luminous giant star that can be located in the constellation of Cancer. The star can not be seen by the naked eye, you need a telescope to see it.

Iota Cancri A is the Bayer Classification for the star. HIP43100 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD74738.

Location of Iota Cancri B

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 Iota Cancri B, the location is 08h 46m 40.00 and +28d45`54.6 .

Proper Motion of Iota Cancri B

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 -46.36 ± 1.66 miliarcseconds/year towards the north and -22.74 ± 2.75 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Iota Cancri B

Iota Cancri B has a spectral type of G8II.... This means the star is a white to yellow luminous giant star. The star has a B-V Colour Index of 0.05 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 9,222 Kelvin.

Iota Cancri B Radius has been calculated as being 1.02 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 710,739.41.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 1.51. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

The star has a companion star which is in orbit close by, it has at least the following companions in close orbit, .

Iota Cancri B Apparent and Absolute Magnitudes

Iota Cancri B has an apparent magnitude of 6.58 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 2.77 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.92. 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 Iota Cancri B

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 17.31 which gave the calculated distance to Iota Cancri B as 188.42 light years away from Earth or 57.77 parsecs. It would take a spaceship travelling at the speed of light, 188.42 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 11.69 which put Iota Cancri B at a distance of 279.01 light years or 85.54 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 Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

Iota Cancri B Facts

Alternative Names

Traditional/Proper NameIota Cancri B
Flamsteed Name48 Cancri
Flamsteed Short Name48 Cnc
Bayer DesignationIota Cancri A
Hipparcos Library I.D.43100
Bonner DurchmusterungBD+29 1823
Henry Draper Designation74738

Visual Facts

Star Typeluminous giant star
Absolute Magnitude2.77 / 1.92
Visual / Apparent Magnitude6.58
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)08h 46m 40.00
Declination (Dec.)+28d45`54.6
Galactic Latitude36.54 degrees
Galactic Longitude195.87 degrees
1997 Distance from Earth17.31 Parallax (milliarcseconds)
 188.42 Light Years
 57.77 Parsecs
2007 Revised Distance from Earth11.69 Parallax (milliarcseconds)
 279.01 Light Years
 85.54 Parsecs
Proper Motion Dec.-46.36 ± 1.66 milliarcseconds/year
Proper Motion RA.-22.74 ± 2.75 milliarcseconds/year
B-V Index0.05
Radial Velocity25.00 ± 1.50 km/s
Spectral TypeG8II...
Colour(G) White to Yellow

Estimated Facts

Calculated Effective Temperature9,222 Kelvin

Sources and Links

SIMBAD SourceLink

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