Melotte 15, IC 1805
The bright star cluster [known as an "open cluster"] centered in this image is known as Melotte15 after its discover, Philibert Jacques Melotte (1880-1961).
Melotte 15 is embedded within and illuminates the central portion of the much larger glowing nebula identified as IC 1805.
The three bright stars in an arc at the center of this image are type "O" stars which are the brightest and most massive stars known. Type O stars are also the shortest lived. While the Sun, a type "G" star, will happily burn its hydrogen fuel for 10 billion years or more, type O stars burn through their much more massive amount of fuel [typically type O stars are 20 to 100 times more massive than our sun] in as short as 3 to 6 million years. A very short lifespan as far as stars go.
Type O stars then end their lives in a spectacular Type II supernova which spreads the elements generated in the core of the star throughout the stellar neighborhood. In fact, the elements that make up our own bodies were created in much earlier supernovas.
The interesting structure in the center of the image is a giant area of hydrogen gas that is caused to glow by the intense ultraviolet radiation from the massive stars of the Melotte 15 star cluster. It is estimated that this illuminated gas is more than 50 light years from the Melotte15 stars.
The Melotte 15 star cluster is estimated to be 7,500 light years away from Earth.
A Google search of IC 1805 will find many more interesting images of IC 1805 and Melotte 15.
October 1, 2016
San Diego Astronomy Association obvserving site at Tierra Del Sol, San Diego County, CA
RC Optical Systems 10" f/9 Ritchey-Chretien, Astro-Physics AP 900, SBIG STT-8033