By Aikaterini Niovi Triantafillaki
Our Sun resides within a cavity in our galaxy known as the Local Bubble. This bubble is thought to be the result of supernova explosions that occurred in the past, pushing the region’s gas outward and creating an empty space. As the Sun orbited the center of the Milky Way, it eventually ended up in its current location within this bubble. Extensive research is being conducted to trace the edges of the Local Bubble and uncover the reasons behind its formation—mainly by focusing on older surrounding molecular clouds.
How the Local Bubble appears near the Sun, along with some molecular clouds and star-forming regions.
In this context, a structure called EOS emerged in the research of Dr. Dharmawardena and Dr. Burkhart. Their work involves analyzing and reconstructing the Milky Way’s molecular clouds in 3D, using innovative techniques. In their observations of existing data, they noticed something… peculiar and dark. Typically, molecular clouds are “seen” through the ultraviolet emission of molecular hydrogen. But this particular cloud was discovered by directly observing in the far-ultraviolet spectrum, where glowing hydrogen molecules fluoresced—“glowing in the dark,” as the authors describe it. And although it glows, its low hydrogen density had made it difficult to detect until now.
So, EOS is a molecular cloud located just 300 light-years away (around 10¹⁵ kilometers) from our solar system, positioned at the edge of the Local Bubble. And it’s a huge structure—if it were visible to the naked eye, it would span a portion of the sky as large as 40 full moons! Despite its low density, its mass is estimated to be around 3,400 times that of the Sun.
The researchers named it EOS, after the Greek goddess of the dawn, and they hope that this discovery will open new pathways in the study of molecular clouds in our galaxy and their evolution—with a dedicated mission under the same name already being proposed.
Watch a fascinating 3D reconstruction on YouTube:
https://www.youtube.com/watch?v=QsPurtQWBTI