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49 Cancri, HD74521, HIP42917, HR3465

49 Cancri is a blue rotating star that can be located in the constellation of Cancer. 49 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.

The Id of the star in the Yale Bright Star Catalogue is HR3465. HIP42917 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD74521.

49 Cancri has alternative name(s), BI Cnc.

Location of 49 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 49 Cancri, the location is 08h 44m 45.04 and +10d 04` 54.2 .

Proper Motion of 49 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 -18.42 ± 0.19 miliarcseconds/year towards the north and -14.41 ± 0.34 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 27.50000 km/s with an error of about 1.40 km/s .

Physical Properties (Colour, Temperature, Radius) of 49 Cancri

49 Cancri has a spectral type of A1p.... This means the star is a blue star. The star is 7491.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24432.8960990400000000s. The star has a B-V Colour Index of -0.06 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 12,136 Kelvin.

49 Cancri Radius has been calculated as being 1.97 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,371,624.46.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.05. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

49 Cancri Apparent and Absolute Magnitudes

49 Cancri has an apparent magnitude of 5.63 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 0.15 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.07. 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 49 Cancri

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 8.00 which gave the calculated distance to 49 Cancri as 407.70 light years away from Earth or 125 parsecs. It would take a spaceship travelling at the speed of light, 407.70 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 7.71 which put 49 Cancri at a distance of 423.04 light years or 129.70 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 7,491.00 Parsecs or 24,432.90 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 49 Cancri

The star is a rotating Alpha2 Canum Venaticorum 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. 49 Cancri brightness ranges from a magnitude of 5.620 to a magnitude of 5.603 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 7.1 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.

49 Cancri Facts

Alternative Names

Traditional/Proper Name49 Cancri
Flamsteed Name49 Cancri
Flamsteed Short Name49 Cnc
Short NameBI Cnc
Hipparcos Library I.D.42917
Yale Bright Star Catalogue (HR) Id3465
Bonner DurchmusterungBD+10 1864
Henry Draper Designation74521

Visual Facts

Star Type star
Absolute Magnitude0.15 / 0.07
Visual / Apparent Magnitude5.63
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)08h 44m 45.04
Declination (Dec.)+10d 04` 54.2
Galactic Latitude29.71 degrees
Galactic Longitude216.71 degrees
1997 Distance from Earth8.00 Parallax (milliarcseconds)
 407.70 Light Years
 125 Parsecs
2007 Revised Distance from Earth7.71 Parallax (milliarcseconds)
 423.04 Light Years
 129.70 Parsecs
Galacto-Centric Distance24,432.90 Light Years / 7,491.00 Parsecs
Proper Motion Dec.-18.42 ± 0.19 milliarcseconds/year
Proper Motion RA.-14.41 ± 0.34 milliarcseconds/year
B-V Index-0.06
Radial Velocity27.50 ± 1.40 km/s
Spectral TypeA1p...
Colour(A) blue

Variable Star Details

Variable Star ClassRotating
Variable Star TypeAlpha2 Canum Venaticorum
Mean Variability Period in Days7.052
Variable Magnitude Range (Brighter - Dimmer)5.603 - 5.620

Estimated Facts

Calculated Effective Temperature12,136 Kelvin

Sources and Links

SIMBAD SourceLink

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