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Mu1 Cancri, 9 Cancri, HD66875, HIP39659, HR3169

Mu1 Cancri is a red pulsating giant star that can be located in the constellation of Cancer. The description is based on the spectral class. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Mu1 Cancri's Alternative Names

(Mu1 Cancri) is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR3169. HIP39659 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD66875.

Mu1 Cancri has alternative name(s) :- , BL Cnc.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John numbered the stars in the constellation with a number and the latin name, this star's Flamsteed designation is 9 Cancri with it shortened to 9 Cnc.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+23 1887.

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

Location of Mu1 Cancri

The location of the 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 star is compared to the celestial equator and is expressed in degrees. For Mu1 Cancri, the location is 08h 06m 18.40 and +22° 38` 07.8 .

Proper Motion of Mu1 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 -9.06 ± 0.31 miliarcseconds/year towards the north and -5.97 ± 0.53 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 29.61000 km/s with an error of about 0.57 km/s .

Physical Properties (Colour, Temperature) of Mu1 Cancri

Mu1 Cancri has a spectral type of M3III. This means the star is a red giant star. The star is 7,591.00 Parsecs from the Galactic Centre or terms of Light Years is 24,759.06 s. The star has a B-V Colour Index of 1.65 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 3,640 Kelvin.

Mu1 Cancri Radius has been calculated as being 29.02 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 20,192,476.17.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 34.41. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Mu1 Cancri Apparent and Absolute Magnitudes

Mu1 Cancri has an apparent magnitude of 5.96 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 -0.46 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.83. 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 Mu1 Cancri

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 5.21 which gave the calculated distance to Mu1 Cancri as 626.03 light years away from Earth or 191.94 parsecs. It would take a spaceship travelling at the speed of light, 626.03 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 4.38 which put Mu1 Cancri at a distance of 744.67 light years or 228.31 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 7,591.00 Parsecs or 24,759.06 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 Mu1 Cancri

The star is a pulsating Slow Irregular 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. Mu1 Cancri brightness ranges from a magnitude of 6.112 to a magnitude of 5.937 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.2 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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Mu1 Cancri Facts

Visual Facts

Primary / Proper / Traditional NameMu1 Cancri
Alternative NamesHD 66875, HIP 39659, HR 3169, 9 Cancri, 9 Cnc, BD+23 1887, BL Cnc
Spectral TypeM3III
Multiple Star SystemYes
Star TypeGiant Star
Colour red
GalaxyMilky Way
Absolute Magnitude-0.46 / -0.83
Visual / Apparent Magnitude5.96
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)08h 06m 18.40
Declination (Dec.)+22° 38` 07.8
Galactic Latitude26.05 degrees
Galactic Longitude199.58 degrees
1997 Distance from Earth5.21 Parallax (milliarcseconds)
 626.03 Light Years
 191.94 Parsecs
2007 Distance from Earth4.38 Parallax (milliarcseconds)
 744.67 Light Years
 228.31 Parsecs
Galacto-Centric Distance24,759.06 Light Years / 7,591.00 Parsecs
Proper Motion Dec.-9.06 ± 0.31 milliarcseconds/year
Proper Motion RA.-5.97 ± 0.53 milliarcseconds/year
B-V Index1.65
Radial Velocity29.61 ± 0.57 km/s
Semi-Major Axis7670.00
Associated / Clustered StarsMu2 Cancri

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.162
Variable Magnitude Range (Brighter - Dimmer)5.937 - 6.112

Estimated Facts

Calculated Effective Temperature3,640 Kelvin

Sources and Links

SIMBAD SourceLink

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