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Rho Leonis, 47 Leonis, HD91316, HIP51624, HR4133

Rho Leonis is a blue pulsating supergiant star that can be located in the constellation of Leo. 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.

Rho Leonis's Alternative Names

Rho Leonis (Rho Leo) is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR4133. HIP51624 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD91316.

Rho Leonis has alternative name(s) :- , rho Leo.

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 47 Leonis with it shortened to 47 Leo.

The Gould star designation is one that was designed by American astronomer, Benjamin Apthorp Gould. Gould stars are predominantly in the Southern and Equatorial constellations but do appear in northern constellations such as Bootes and Orion. The star has the designation 14 G. Leonis. There are no stars with a Gould designation in Ursa Major for example.

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+10 2166.

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

Location of Rho Leonis

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 Rho Leonis, the location is 10h 32m 48.68 and +09° 18` 23.7 .

Proper Motion of Rho Leonis

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 -3.40 ± 0.10 miliarcseconds/year towards the north and -5.93 ± 0.18 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 42.00000 km/s with an error of about 0.80 km/s .

Physical Properties (Colour, Temperature) of Rho Leonis

Rho Leonis has a spectral type of B1Ib SB. This means the star is a blue supergiant star. The star has a B-V Colour Index of -0.14 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 16,194 Kelvin.

Rho Leonis Radius has been calculated as being 35.50 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 24,703,131.70.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 33.75. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is -0.89 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Rho Leonis Apparent and Absolute Magnitudes

Rho Leonis has an apparent magnitude of 3.84 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 -7.38 If you used the 2007 Parallax value, you would get an absolute magnitude of -7.27. 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 Rho Leonis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.57 which gave the calculated distance to Rho Leonis as 5722.16 light years away from Earth or 1754.39 parsecs. It would take a spaceship travelling at the speed of light, 5722.16 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 0.60 which put Rho Leonis at a distance of 5436.06 light years or 1666.67 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.

Variable Type of Rho Leonis

The star is a pulsating Alpha Cygnus 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. Rho Leonis brightness ranges from a magnitude of 3.812 to a magnitude of 3.791 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 3.4 days (variability).

Meteor Showers Radiating from near Rho Leonis

The Rho Leonids Meteor Shower radiants from a point near this star. The meteor shower runs typically between Feb 13 - Mar 13 with a peak date of Mar 1 - 4. The speed of a meteor in the shower is 66 Km/s.

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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Rho Leonis Facts

Visual Facts


Primary / Proper / Traditional NameRho Leonis
Alternative NamesRho Leo, HD 91316, HIP 51624, HR 4133, 14 G. Leonis, 47 Leonis, 47 Leo, BD+10 2166, rho Leo
Spectral TypeB1Ib SB
Multiple Star SystemYes
Star Type very luminous Supergiant Star
Colour blue
GalaxyMilky Way
ConstellationLeo
Absolute Magnitude-7.38 / -7.27
Visual / Apparent Magnitude3.84
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)10h 32m 48.68
Declination (Dec.)+09° 18` 23.7
Galactic Latitude52.77 degrees
Galactic Longitude234.89 degrees
1997 Distance from Earth0.57 Parallax (milliarcseconds)
 5722.16 Light Years
 1754.39 Parsecs
2007 Distance from Earth0.60 Parallax (milliarcseconds)
 5436.06 Light Years
 1666.67 Parsecs
Proper Motion Dec.-3.40 ± 0.10 milliarcseconds/year
Proper Motion RA.-5.93 ± 0.18 milliarcseconds/year
B-V Index-0.14
Radial Velocity42.00 ± 0.80 km/s
Iron Abundance-0.89 ± 9.99 Fe/H

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeAlpha Cygnus
Mean Variability Period in Days3.427
Variable Magnitude Range (Brighter - Dimmer)3.791 - 3.812

Estimated Facts


Calculated Effective Temperature16,194 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
91316+10 2166.0A3.80000-9.00000-6.00000B0Blue/White
B1940

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