The vacuum of space isn’t really a vacuum. A vacuum is defined by Merriam-Webster as “a space absolutely devoid of matter.” However, even empty space has some matter in it. This matter, in the form of dust and gas, tends to collect into what are called molecular clouds. Without anything interfering with them they continue to float as a cloud.
When something happens to interrupt the balance of the molecular cloud, some of that dust and gas starts clumping together. As more and more of this dust and gas clump together gravity takes over and starts forming stars. One way that the balance of a molecular cloud can be interfered with is by a supernova remnant, the remains of an exploded star. Plasma jets, radiation, and other clouds can also interact with these clouds.
It is difficult to observe this process in action and there are too many variables to use computer modeling to determine how it all happens. Recently, an international team of researchers used something a little different to model the interaction between a supernova remnant and a molecular cloud, a laser and a foam ball.
The team used a high-power laser to create a blast wave that spread through a chamber of gas with a foam ball inside of it. Using X-ray imaging, they were able to observe the compression of the foam ball being hit by the blast wave.
X-ray radiographs of the foam ball: (a) without the influence of a blast wave, for reference; (b) at t = 500 ns after the beginning of the main laser pulse. Credit: Bruno Albertazzi et al.These observations may help us understand the mechanisms for triggering star formation. Such interactions can impact star formation rate, the evolution of a galaxy, and explain the formation of some of the most massive stars.
This experiment was more of a proof-of-concept than anything, giving researchers a new way to use lasers to find answers about astronomical questions that are difficult to deduce by other means. And who doesn’t like the idea of using lasers… for anything?
The blast wave caused a deformation of the foam ball which ended up being compressed on part of it while some of it ended up being stretched out, changing the average density of the material. In their subsequent experiments the researchers will have to take this into account to get an accurate measurement of the compressed material and the shockwave’s impact on star formation. Soon the team will be testing how radiation, magnetic fields, and turbulence can affect star formation in molecular clouds.
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Header: Illustration of the evolution of a massive cloud which indicates the importance of SNR propagation in forming new stars. CREDIT: Albertazzi et al.
