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"
X-Rays and the Circinus Pulsar
13/09/2001
A bizarre stellar corpse 19,000 light-years from Earth, pulsar PSR B1509-58 beckons from the small southern constellation of Circinus. Like its cousin at the heart of the Crab nebula, the Circinus pulsar is a rapidly spinning, magnetized neutron star. Seen in this false-color Chandra Observatory image, the environment surrounding this cosmic powerhouse glows in high energy x-rays. The Circinus pulsar itself, thought to generate more than 7 quadrillion volts (7 followed by 15 zeros), lies within the knot of bright emission near the center of the picture. Stretching toward the bottom left, x-ray emission traces a jet of particles almost 20 light-years long that seems to arise from the pulsar's south pole, while the arc of bright emission above the central knot is likely a shockwave produced by particles driven from the pulsar's equator. Near the top of the picture, lower energy x-ray emission shown in green is from gas shock-heated to millions of degrees Celsius. The shocked gas was produced by debris blasted out from the stellar explosion that created the Circinus pulsar.