Our Milky Way galaxy contains clouds of gas and dust called molecular clouds. Perseus and Taurus are two such famous clouds. Previous research had astronomers observing them on 2D maps, and it seemed that these two molecular clouds were scattered in different places in space. However, the PerTau project, using data from the Gaia satellite, created the first accurate 3D map of them. This 3D visualization revealed a surprising thing: these two clouds are not actually separate, but are based on the surface of a very large spherical cavity (an empty sphere). This is not just an image, but a giant 3D cavity in real space, in which the space inside is mostly empty and there are dense gas and dust clouds only on the edges. This cavity is approximately 500 light-years big, meaning it is very huge, that is, even if you travel at the speed of light, it will take 500 years to cross this empty space.
How this bubble was formed is a very interesting story. According to scientists, approximately 6 to 22 million years ago, there were one or more supernova explosions, meaning one or more massive stars exploded at the end of their lives. When a star explodes, its blast pushes the surrounding gas and dust with force, like a giant cosmic shock-wave. This blast was so powerful that it pushed the surrounding gas and dust out from the center, and created a huge empty bubble in the middle. But the effect of the blast was not limited to just destruction; the gas that accumulated at the edges of the bubble in this process is now in the form of Perseus and Taurus molecular clouds. These clouds follow the rim of the bubble in a curved shape, and this is the place where new stars are formed, meaning the supernova indirectly triggers star formation.
This process had the greatest impact on star formation. When the shock-wave of the supernova pushed the gas at the edge, the density of the gas there increased significantly. According to physics, where there is more mass, gravity also increases. Due to this high density and gravity, the gas clouds began to contract and they started giving birth to new stars. The thousands of new stars that we see forming in the Perseus and Taurus clouds today are actually the result of that same old explosion.
3D visualization made it even clearer that this bubble isn't a perfect sphere, but a slightly distorted bubble with gas clouds irregularly wrapped around the edges, and each cloud has its own complex structure. This 3D mapping shows that these clouds don't just appear close together in a picture, but exist in real space with a curved surface and depth. This means that the supernova's blast pushed gas in one direction, gathered gas in the other direction, and shaped the new star nurseries. Visualize a star exploding, creating a blast, and the blast waves enveloping the surrounding gas, creating a bubble in which the center region becomes empty and gas accumulates at the edges. This gas then collapses, giving birth to new stars, a process of cosmic recycling.
And that's the beauty of this discovery: we not only saw a structure, but also understood how the long-term impact of supernova explosions affects space and how this regulates the natural star formation process. The empty space inside the bubble and the dense clouds at the edges create a perfect contrast, showing that creation can occur even after destruction. Scientists also noted that the pattern of gas velocities and density gradients inside and outside the bubble influences future sites of star formation, and that this process is always repeated in the galaxy, like a cosmic loop – a star explodes, explodes, forms a bubble, gas accumulates at the edges, and new stars form. Basically, the Perseus–Taurus Super-shell provides us with proof that an organized pattern exists amidst the chaos of space, where destruction and creation go hand in hand. Through modern 3D mapping, we finally understood that what we previously thought was just a flat 2D image is actually a dynamic 3D structure, full of motion, depth, and cosmic history, allowing us to visually and real-time understand the processes of star formation in the universe.
Source: https://sbialy.wixsite.com/pertau