A new image from the Hubble Space Telescope shows a nebula in the gorgeous colors of autumn, just in time for leaf-changing season in the northern hemisphere. It shows a part of a nebula called Westerhout 5, located 7,000 light-years away and also known as the Soul Nebula.
It is an emission nebula, meaning that its gorgeous colors and shapes are created by gas which has become ionized by starlight from bright, hot stars. As very massive stars are born and give off large gusts of radiation and streams of particles called stellar winds, these blow away nearby material which prevents more stars from forming too close. This creates cavities within the nebula, and in between these cavities more gas is pushed together. Then more stars can form in these now denser regions.
One feature of note in this image is the dark region in the upper middle, which is an object called a free-floating Evaporating Gaseous Globule (frEGG). This dense pocket of gas is more resistant to the radiation which is ionizing the gas around it, creating a kind of “egg” from which new stars can be born. The best-known example of EGGs is in the famous Pillars of Creation image, also taken by Hubble, which found these pockets of denser gas that appeared as bumps on the nebula’s columns.
In this image, the EGGs are of a type called free-floating because they aren’t attached to a particular structure, but they do have a recognizable tadpole-like shape with a head and a tail. Eventually, these pockets of gas may incubate new stars as the density in the surrounding area increases and they become hotter, allowing a protostar to form inside.