Solar system is at the center of giant space bubble, now we know why
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This bubble in space was found decades ago. But clear explanation about its existence or Solar System's position within it was not available
Our Solar System is situated almost exactly in the middle of a giant, relatively empty bubble in space. This mysterious bubble is 1000 lightyears across. Inside the bubble, temperature of the interstellar medium is greater than that outside the bubble.
For years, presence of this bubble has baffled scientists. A strong explanation behind existence of this bubble, known as Local Bubble, was not present. But now we may know why this bubble exists.
A team of astronomers led by the Harvard & Smithsonian Center for Astrophysics (CfA) has mapped the Local Bubble with highest precision till date. The team has found that a number of supernovas (explosion of stars) formed the bubble millions of years ago. Supernovas can carve a cavity in interstellar medium.
Astronomers found that the bubble's history started 14.4 million years ago. This started with formation of stars. Supernovas of these short-lived stars followed. The energy of the explosion pushed the interstellar material away and formed the bubble inside which temperature was higher than thant outside it. Density of the interstellar material inside the bubble is less than outside.
Astronomers found that there were 15 supernovas inside the bubble.
The Local Bubble is still growing at a rate of 6.7 kilometres per second. This is quite a slow speed when we consider events in space.
But why is Solar System right in the middle of the Local Bubble? Well that's purely due to chance. When the first supernova took place, Solar System was quite away from it. But Solar System's travel around the galaxy brought it (by chance) in the middle of the Local Bubble.