The Heart and Soul Nebulas in Elemental Color

About This Photograph

These two emission nebulas in the constellation of Cassiopeia are composed of gasses made visible due to ionization by the ultraviolet light coming from the young, hot star clusters near their centers. These stars were likely born from these clouds, but now they are hollowing out huge caverns in their previous nursery. Cones and pillars of gas can be found around the borders of these caverns, formed when denser clumps of gas and dust erode more slowly, leaving wakes pointing away from the bright central stars.

This photograph was taken using special filters to isolate the light emitted by sulfur, hydrogen, and oxygen. These exposures were then mapped to red, yellow, and blue colors, respectively. Sulfur is more easily ionized than hydrogen, and hydrogen is more easily ionized than oxygen. Therefore the range of colors roughly maps to the amount of ultraviolet light energy available to ionize the gasses. Clearly this is highest near the bright central stars.