NGC 6559 - the HRGB star factory

NGC 6559 is an emission nebula, a star forming region that lies about 5000 light-years away from Earth, just east-northeast of its much more famous neighbor, the Lagoon Nebula (Messier 8) – and has formed from the same molecular cloud – in the constellation of Sagittarius. These brilliant hot young stars born out of the cloud energise the hydrogen gas still present around them in the nebula . The gas then re-emits this energy, producing the glowing threadlike red cloud seen near the centre of the image. This object is known as an emission nebula. The bluish patch next to the red emission nebula shows the light from the recently formed stars being scattered — reflected in many different directions — by the microscopic particles in the nebula. Known as a reflection nebula, this type of object usually appears blue because the scattering is more efficient for these shorter wavelengths of light.