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Asellus Borealis (Gamma Cancri) - HD74198 - HIP42806 - HR3449

Asellus Borealis (Gamma Cancri) is a blue subgiant star that can be located in the constellation of Cancer. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Gamma Cancri is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR3449. HIP42806 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD74198.

Asellus Borealis has alternative name(s), 43 Cancri , 43 Cnc.

Location of Asellus Borealis

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 Asellus Borealis, the location is 08h 43m 17.21 and +21d28`06.9 .

Proper Motion of Asellus Borealis

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 -39.48 ± 0.11 miliarcseconds/year towards the north and -103.51 ± 0.21 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Asellus Borealis

Asellus Borealis has a spectral type of A1IV. This means the star is a blue subgiant star. The star is 7442.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24273.0760604800000000s. The star has a B-V Colour Index of 0.01 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 9,392 Kelvin.

Asellus Borealis Radius has been calculated as being 2.00 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,392,706.45.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.29. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Asellus Borealis Apparent and Absolute Magnitudes

Asellus Borealis has an apparent magnitude of 4.66 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 1.23 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.94. 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 Asellus Borealis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 20.58 which gave the calculated distance to Asellus Borealis as 158.49 light years away from Earth or 48.59 parsecs. It would take a spaceship travelling at the speed of light, 158.49 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 18.00 which put Asellus Borealis at a distance of 181.20 light years or 55.56 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 7,442.00 Parsecs or 24,273.08 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.

Asellus Borealis Facts

Alternative Names

Traditional/Proper NameAsellus Borealis
Short Name43 Cnc
Bayer DesignationGamma Cancri
Alternative Name(s)43 Cancri
Hipparcos Library I.D.42806
Yale Bright Star Catalogue (HR) Id3449
Bonner DurchmusterungBDD+21 1895
Henry Draper Designation74198

Visual Facts

Star Typesubgiant star
Absolute Magnitude1.23 / 0.94
Visual / Apparent Magnitude4.66
Naked Eye VisibleYes - Ref: Wiki
Right Ascension (R.A.)08h 43m 17.21
Declination (Dec.)+21d28`06.9
Galactic Latitude33.73 degrees
Galactic Longitude204.17 degrees
1997 Distance from Earth20.58 Parallax (milliarcseconds)
 158.49 Light Years
 48.59 Parsecs
2007 Revised Distance from Earth18.00 Parallax (milliarcseconds)
 181.20 Light Years
 55.56 Parsecs
Galacto-Centric Distance24,273.08 Light Years / 7,442.00 Parsecs
Proper Motion Dec.-39.48 ± 0.11 milliarcseconds/year
Proper Motion RA.-103.51 ± 0.21 milliarcseconds/year
B-V Index0.01
Radial Velocity28.70 ± 2.80 km/s
Spectral TypeA1IV
Colour(A) blue

Estimated Facts

Calculated Effective Temperature9,392 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.


Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
74198+21 1895.0A4.70000-103.00000-43.00000A0White
+21 1897.0B8.70000-2.00000-12.000001919
P12.400001908
BQ12.900001908

Location of Asellus Borealis in Cancer


Asellus Borealis (Gamma Cancri) Location in Cancer

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


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