Universe Guide


Rho Leonis, 47 Leonis, HD91316, HIP51624

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

Rho Leonis is the Bayer Classification for the star. 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. The Id of the star in the Gould Star Catalogue is 14. Stars in the southern hemisphere are more likely to have a Gould Id than the northern hemisphere. For example, there are no Gould classified stars in Ursa Major.

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

Location of Rho Leonis

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 Rho Leonis, the location is 10h 32m 48.68 and +09d18`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.

Rho Leonis Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 280000.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

Physical Properties (Colour, Temperature, Radius) 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. 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.

Rho Leonis Facts

Alternative Names

Flamsteed Name47 Leonis
Flamsteed Short Name47 Leo
Short Namerho Leo
Bayer DesignationRho Leonis
Hipparcos Library I.D.51624
Bonner DurchmusterungBD+10 2166
Gould I.D.14
Henry Draper Designation91316

Visual Facts

Star Typesupergiant star
Absolute Magnitude-7.38 / -7.27
Visual / Apparent Magnitude3.84
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)10h 32m 48.68
Declination (Dec.)+09d18`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 Revised 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
Spectral TypeB1Ib SB
Colour(B) blue

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

Luminosity (x the Sun)280,000.0000000
Calculated Effective Temperature16,194 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
91316+10 2166.0A3.80000-9.00000-6.00000B0Blue/White

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