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21 Leonis Minoris, HD87696, HIP49593, HR3974

21 Leonis Minoris is a blue main sequence dwarf star that can be located in the constellation of Leo Minor. 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.

21 Leonis Minoris's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR3974. HIP49593 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD87696. The Gliese ID of the star is GL 378.3. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

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 21 Leonis Minoris with it shortened to 21 LMi.

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+35 2110.

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

Location of 21 Leonis Minoris

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 21 Leonis Minoris, the location is 10h 07m 25.73 and +35° 14` 40.9 .

Proper Motion of 21 Leonis Minoris

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 0.62 ± 0.11 miliarcseconds/year towards the north and 52.90 ± 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 -11.40000 km/s with an error of about 0.90 km/s .

21 Leonis Minoris 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 10.60 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of 21 Leonis Minoris

21 Leonis Minoris has a spectral type of A7V. This means the star is a blue main sequence dwarf star. The star is 7,416.00 Parsecs from the Galactic Centre or terms of Light Years is 24,188.27 s. The star has a B-V Colour Index of 0.19 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,827 Kelvin.

21 Leonis Minoris Radius has been calculated as being 1.79 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,247,886.18.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 1.81. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

21 Leonis Minoris Apparent and Absolute Magnitudes

21 Leonis Minoris has an apparent magnitude of 4.49 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 2.26 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.24. 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 21 Leonis Minoris

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 35.78 which gave the calculated distance to 21 Leonis Minoris as 91.16 light years away from Earth or 27.95 parsecs. It would take a spaceship travelling at the speed of light, 91.16 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 35.41 which put 21 Leonis Minoris at a distance of 92.11 light years or 28.24 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 7,416.00 Parsecs or 24,188.27 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

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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21 Leonis Minoris Facts

Visual Facts


Primary / Proper / Traditional Name21 Leonis Minoris
Alternative NamesHD 87696, HIP 49593, HR 3974, 21 LMi, BD+35 2110, Gliese 378.3
Spectral TypeA7V
Multiple Star SystemNo / Unknown
Star Type main sequence Dwarf Star
Colour blue
GalaxyMilky Way
ConstellationLeo Minor
Absolute Magnitude2.26 / 2.24
Visual / Apparent Magnitude4.49
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)10h 07m 25.73
Declination (Dec.)+35° 14` 40.9
Galactic Latitude54.26 degrees
Galactic Longitude189.47 degrees
1997 Distance from Earth35.78 Parallax (milliarcseconds)
 91.16 Light Years
 27.95 Parsecs
2007 Distance from Earth35.41 Parallax (milliarcseconds)
 92.11 Light Years
 28.24 Parsecs
Galacto-Centric Distance24,188.27 Light Years / 7,416.00 Parsecs
Proper Motion Dec.0.62 ± 0.11 milliarcseconds/year
Proper Motion RA.52.90 ± 0.18 milliarcseconds/year
B-V Index0.19
Radial Velocity-11.40 ± 0.90 km/s
Eccentricity0.22
Semi-Major Axis8888.00
Stellar Luminosity (Lsun)10.60

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Estimated Facts


Calculated Effective Temperature7,827 Kelvin

Sources and Links


SIMBAD SourceLink

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