Melotte 15: Within ‘The Heart’ Nebula

7500 light years away from Earth, The Heart Nebula is located in the Perseus Arm of the Galaxy in the constellation Cassiopeia. The nebula is formed by plasma of ionized hydrogen and free electrons, and this open cluster of stars  contains a few bright stars nearly 50 times the mass of our Sun, and many more dim stars that are only a fraction of our Sun’s mass. The cluster used to contain a microquasar that was expelled millions of years ago. [image via]


NGC 6523: The Lagoon Nebula

Estimated to be between 4,000 to 6,000 light years from the Earth, in the direction of the Sagittarius constellation. It is classified as both an emission nebula and an HII region. The Lagoon Nebula was discovered by Guillaume Le Gentil in 1747 and is one of only two star-forming nebulae faintly visible to the naked eye from mid-northern latitudes. Seen with binoculars, it appears as a distinct oval cloudlike patch with a definite core. [image via]