mardi 10 juin 2008

Leo 4

a Leonis , Alpha Leonis.
Regulus
Distance 77,5 Light Years.
Visual Magnitude 1,35
Color B-V –0,11

Names For This Star
Regulus is Latin and means "The Little King". According to Allen the name reflects a common belief that the star ruled the affairs of heaven. Rex is another Latin name for the star, meaning "The King."
A further name for the star is the Latin Cor Leonis, meaning "The Heart of the Lion." This name reflects the position of Regulus in the figure of the Lion as it is usually visualized.
Other names for the star are Al Kalb al Asad or Kabeleced. These names are derived from the Arabic name Al Kalb al Asad meaning nothing more than "The Heart of the Lion."
Description of the Star
Regulus is a hot, blue B7V main sequence star having a luminosity (The luminosity of a star represents the total output of radiant energy per second. We can grasp this quantity most easily by thinking of the luminosity of the star in comparison with that of our sun. A star 100 times as luminous as the sun, would emit 100 times as much radiant energy per second as our sun does) about 140 times that of the sun and about 3.4 times the diameter. The spectral type implies an effective temperature of 13,000 K and a diameter about 3 times that of the sun.
This star is in fact the A component of a multiple star system. The B and C components are a close binary pair revolving together with a separation of 4.2 arc sec from A. This corresponds to a separation of about 100 AU, that is, two and a half times the distance between the sun and Pluto. The period is 2000 years.
Regulus B is an orange K1V main sequence star having a Visual Magnitude of 8.13. This star has slightly more than 1/4 of the luminosity of the sun, 70% of the sun's mass, and 80% of the sun's radius. Regulus C is a 13th magnitude dwarf having a luminosity of 1/330 of that of the sun.

Denebolis

b Leonis, Beta Leonis.
Denebola : ذنب الاسد.






Distance Light Years : 36,2.
Visual Magnitude : 2,14.
Color B-V: 0,09.

Names For This Star

This star is also known as Deneb Aleet. The name of the star derives from the Arabic name Al Dhanab al Asad, "The Lion's Tail."
Description of the Star

Denebola is a white A3V main sequence star. The star is 1.5 times the diameter of the sun about 15 times as luminous. The spectral type implies an effective temperature of 9100 K. The luminosity suggests a mass about 2.3 times the mass of the sun.
Denebola is a double star. The physically related B component is of Visual Magnitude 15.7. The star is separated by 40 arc sec from the primary corresponding to a projected separation of 440 AU, that is 11 times the radius of the solar system out to Pluto.


γ1 Leo
Algieba: الجبهة

θ Leo
Chertan, Chort, Coxa : الخرت



ζ Leo
Adhafera, Aldhafera, Aldhafara: الضفيره


λ Leo
Alterf, Al Terf: الطرف


μ Leo
Rasa: رأس الأسد


ε LeoRas Elased, Ras Elased Australis, Algenubi : رأس الأسد

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