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Calendar of astronomy, April sky

Constellation Bootes

 Automatic translationAutomatic translation Category: children
Updated January 21, 2013

In the spring, a triangle formed by the characteristic star Arcturus (α Bootis) of the constellation Bootes, Spica (α Virginis) of the Virgin and Regulus (α Regulus) Leo, help the observer to reper in the night sky. This celestial triangle is called by astronomers the triangle orientation spring.
The constellation Bootes is a boreal constellation, visible from the northern hemisphere. Its brightest stars in the sky draw a large kite (see larger image). We find also near the constellation Bootes, a massive star clusters, M3 (Messier 3). The star cluster M3 is located between Arcturus Bootes (α Bootis) and double stars, the brightest of hunting dogs (Cor Caroli). Arcturus, the main star of Bootes is a giant orange 30 times brighter than our Sun, it is the fourth brightest star in the sky. It is located in the extension of the curve of the tail of the Great Bear. Its name means Guardian Bear in ancient Greek.

 

nota: A constellation is a group of stars that sufficiently close to the celestial vault are gave the appearance of an imaginary figure drawn in the sky.

nota: By convention, the names of the stars in a constellation are prefixed by a Greek letter followed by the first 3 letters of the constellation, for example:
α  Ori, β Ori,... (Greek letters: α β γ δ ε ζ η θ ι κ λ μ ν ξ ο π ρ ς σ τ υ φ χ ψ ω).


nota: a light year is exactly 9 460 895 288 762 850 meters.

nota: M is the mark of the Messier catalog, a catalog of astronomical objects look like diffuse nebulae or galaxies.

Image: Constellation Bootes. Image reworked from the Open Source software Stellarium.

 Constellation Bootes

Star cluster M3

    

The star cluster M3 is a huge ball of stars very old, much older than our Sun, about 10 billion years. Its stars roamed the Galaxy when the Galaxy itself was very young. Many star clusters of its age have gone on some 200 globular clusters that survive today, M3 is one of the biggest and brightest star clusters. It is easily visible in the Northern hemisphere with binoculars in the constellation of the Hunting Dogs.
The star cluster M3 is between Arcturus Bootes (α Bootis) and double stars, the brightest of hunting dogs (Cor Caroli). The apparent magnitude of the cluster M3 is 6.3, just above the limit of visibility with the naked eye. In binoculars you will see a whitish spot and diffuse. If most of the cluster stars are older than 10 billion years, a large number of stars are blue, so young, a few hundred million years. The object was discovered by Charles Messier in 1764 but William Herschel who around 1784 realized it was a cluster of stars. M3 contains a considerable number of stars, about half a million, most stars are old and red. Light takes about 35,000 years to reach us from M3, which spans about 150 light-years. This large globular cluster hosts many variable stars, stars whose brightness varies, while most stars are almost constant brightness, which is its distinctive feature.

 

The center of this cluster is rich in stars, his heart is half the mass of the cluster. Seen through a telescope, it is one of the most beautiful objects in the sky of the northern hemisphere.

nota: M is the mark of the Messier catalog, a catalog of astronomical objects look like diffuse nebulae or galaxies.

Image: Amas d'étoiles M3. La photo est un composite d'images bleues et rouges. 
Crédit & Copyright: S. Kafka & K. Honeycutt (Indiana University), WIYN, NOAO, NSF

 Star cluster M3
 
           
 
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