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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 LeoMinor. 21 Leonis Minoris is the brightest star in Leo Minor 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 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 Gliese GL378.3. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Ref : Star Names.

Location of 21 Leonis Minoris

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 21 Leonis Minoris, the location is 10h 07m 25.73 and +35d 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.

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 9.0000000 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 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 7416.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24188.2735910400000000s. 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. 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.

21 Leonis Minoris Facts

Alternative Names

Traditional/Proper Name21 Leonis Minoris
Flamsteed Name21 Leonis Minoris
Flamsteed Short Name21 LMi
Hipparcos Library I.D.49593
Yale Bright Star Catalogue (HR) Id3974
Bonner DurchmusterungBD+35 2110
Gliese ID378.3
Henry Draper Designation87696

Visual Facts

Star Typemain sequence dwarf star
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.)+35d 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 Revised 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
Spectral TypeA7V
Colour(A) blue

Estimated Facts

Luminosity (x the Sun)9.0000000
Calculated Effective Temperature7,827 Kelvin

Sources and Links

SIMBAD SourceLink

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