Le trapeze d'Orion - Trapezium Multiple Star System in Orion - Le Trapeze d'Orion est...

Le trapeze d'Orion - Trapezium Multiple Star System in Orion - Le Trapeze d'Orion est parmi les plus jeunes amas ouverts connus, avec de nouvelles etoiles toujours en formation dans cette region. The Trapezium is the most famous multiple star system in the entire night sky. Located at the very heart of M42, the Orion Nebula, it is one of the youngest star clusters known. The four brightest stars in the Trapezium (A, B, C and D) are easily visible in a four inch telescope with decent optical quality under good seeing conditions. They range in brightness from magnitude 5 to magnitude 8. They can be seen merged together as one star to the unaided eye as the middle star in the sword of Orion. The image above shows the four brightest stars of the Trapezium at the center of the photo. The core of M42 surrounding the Trapezium is a blue - green color from the predominantly green spectral emission line of Oxygen III, with a smaller amount of blue - green mixed in from the hydrogen - beta emission line. These particular wavelengths also happen to be the wavelengths to which the human visual system is most sensitive for color vision. Much of the rest of the Orion Nebula has a lot of red hydrogen - alpha emission, but the eye is not very sensitive to this wavelength. Some red can be seen in the brightest parts of the nebula that emit hydrogen - alpha light by observers with sensitive color vision. For most people however, if they see any color at all, it will be a very pale green, or blue - green, from the Oxygen III spectral lines