Nebula
A nebula is a giant cloud of gas (mostly hydrogen and helium) and cosmic dust situated between stars in the interstellar medium. Nebulae serve as sites of stellar birth and death—including emission nebulae that glow from ionized gas, reflection nebulae that scatter starlight, and dark nebulae that obscure background stars.
Source: science.nasa.gov
APODs including "Nebula"
WR124: Stellar Fireball
09/11/1998
Some stars explode in slow motion. Rare, massive Wolf-Rayet stars are so tumultuous and hot they are disintegrating right before our telescopes. Glowing gas globs each over 30 times more massive than the Earth are being expelled by a violent stellar wind. Wolf-Rayet star WR124, visible near the image center, is thus creating the surrounding nebula known as M1-67. Why this star has been slowly blowing itself apart over the past 10,000 years remains unclear. WR124 is 15,000 light-years away towards the constellation of Sagitta.