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CU Cancri

CU Cancri Facts

CU Cancri's Alternative Names

HIP41824 is the reference name for the star in the Hipparcos Star Catalogue. The Gliese ID of the star is GJ 2069A. The star was added to the Gliese catalogue in 1970 by Richard van der Riet Woolley hence the GJ prefix rather than GL prefix.Star Names.

CU Cancri has alternative name(s) :- , CU Cnc.

More details on objects' alternative names can be found at Star Names .

Location of CU Cancri

The location of the main sequence star in the night sky 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 object is compared to the celestial equator and is expressed in degrees. For CU Cancri, the location is 08h 31m 37.72 and +19° 23` 40.2 .

Radial Velocity and Proper Motion of CU Cancri

Proper Motion

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 -94.98 ± 4.20 milliarcseconds/year towards the north and -254.94 ± 8.22 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -32.10 km/s with an error of about 43.50 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties (Colour, Temperature) of CU Cancri

CU Cancri Colour and Temperature

CU Cancri has a spectral type of M5Ve. This means the star is a red main sequence star. The star has a B-V Colour Index of 1.85 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 2,579 Kelvin.

CU Cancri Radius

Radius has been calculated as being 0.25 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 173,929.65.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 0.22. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

CU Cancri Apparent and Absolute Magnitudes

CU Cancri has an apparent magnitude of 11.90 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 11.36 If you used the 2007 Parallax value, you would get an absolute magnitude of 11.68. 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 CU Cancri

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 78.05 which gave the calculated distance to CU Cancri as 41.79 light years away from Earth or 12.81 parsecs. It would take a spaceship travelling at the speed of light, 41.79 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 90.37 which put CU Cancri at a distance of 36.09 light years or 11.07 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.

Using the 2007 distance, the star is roughly 2,283,335.49 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.

The star's Galacto-Centric Distance is 7,410.00 Parsecs or 24,168.70 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of CU Cancri

The star is a eruptive Eruptive s of the UV variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. CU Cancri brightness ranges from a magnitude of 11.725 to a magnitude of 10.878 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 1.2 days (variability).

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.

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Additional CU Cancri Facts and Figures

Visual Facts


Primary / Proper / Traditional NameCU Cancri
Alternative NamesHIP 41824, Gliese 2069A, CU Cnc
Spectral TypeM5Ve
Constellation's Main StarNo
Multiple Star SystemYes
Star Type Main Sequence Dwarf Star
ColourRed
GalaxyMilky Way
ConstellationCancer
Absolute Magnitude 11.36 / 11.68
Visual / Apparent Magnitude11.90
Naked Eye VisibleRequires a 4.5 - 6 Inch Telescope - Magnitudes
Right Ascension (R.A.)08h 31m 37.72
Declination (Dec.)+19° 23` 40.2
Galactic Latitude30.45 degrees
Galactic Longitude 205.37 degrees
1997 Distance from Earth78.05 Parallax (milliarcseconds)
 41.79 Light Years
 12.81 Parsecs
2007 Distance from Earth90.37 Parallax (milliarcseconds)
 36.09 Light Years
 11.07 Parsecs
 2,283,335.49 Astronomical Units
Galacto-Centric Distance24,168.70 Light Years / 7,410.00 Parsecs
Proper Motion Dec.-94.98 ± 4.20 milliarcseconds/year
Proper Motion RA.-254.94 ± 8.22 milliarcseconds/year
B-V Index1.85
Radial Velocity-32.10 ± 43.50 km/s
Eccentricity0.30
Semi-Major Axis9674.00

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassEruptive
Variable Star TypeEruptive s of the UV
Mean Variability Period in Days1.171
Variable Magnitude Range (Brighter - Dimmer)10.878 - 11.725

Estimated Calculated Facts


Radius (x the Sun)0.22
Effective Temperature2,579 Kelvin

Sources and Links


SIMBAD SourceLink

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
A13.30000-256.00000-119.00000
B15.20000-256.00000-119.000001936

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