A new image from the Hubble Space Telescope shows the nebula in beautiful autumn colors, just in time for the northern hemisphere’s leaf changing season. It shows a part of the nebula called Westerhout 5, located 7,000 light years away and also known as the Soul Nebula.
It is an emission nebula, meaning its beautiful colors and shapes are created by gas ionized by starlight from bright, hot stars. When very massive stars are born and emit huge blasts of radiation and streams of particles called stellar winds, this blows away nearby material, preventing more stars from forming too close. This creates cavities within the nebula, and between these cavities more gas is pushed together. Thus, more stars can form in this now denser region.
One feature to note in this image is the dark area in the top center, which is an object called a free-floating Evaporating Gaseous Globule (frEGG). These pockets of dense gas are more resistant to radiation that ionizes the surrounding gas, thus creating a kind of “egg” that can give birth to new stars. The most famous example of EGG is in the famous Pillars of Creation image, also taken by Hubble, which discovered pockets of denser gas that appear as lumps in the columns of the nebula.
In this picture, the EGG is of the type called free floating because it is not attached to a particular structure, but has a tadpole-like shape that can be identified by its head and tail. Ultimately, these pockets of gas can incubate new stars as the density in the surrounding area increases and becomes hotter, allowing protostars to form within them.