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Millions of years ago, several supernova explosions led to the creation of a unique low-density bubble called the Local Hot Bubble (LHB). At least this is what scientists believe built this structure. Our solar system sits inside this cavity that stretches at least 1,000 light-years. It is a million degrees in temperature, but since its atoms are so sparse, the heat doesn't affect everything that resides inside it.
Scientists from the Max Planck Institute for Extraterrestrial Physics (MPE) recently found something astounding inside the LHB. Astrophysicist Michael Yeung, Michael Freyberg, and their team members discovered the presence of an interstellar tunnel towards Centaurus.
The study was published in Astronomy & Astrophysics.
Yeung and other members of the team used eROSITA, a powerful X-ray telescope aboard a space observatory, to map the LHB in detail. The telescope operates 1.5 million kilometres from Earth, giving it a unique view of the X-ray sky.
They divided the sky into 2,000 sections and analysed each of them. They discovered that LHB is not a uniform sphere. Instead, it is more perpendicular to the galactic plane.
Freyberg then noted that the bubble is shaped like a bipolar nebula. Along with this, they found the startling interstellar tunnel.
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"What we didn't know was the existence of an interstellar tunnel towards Centaurus, which carves a gap in the cooler interstellar medium," Freyberg stated.
Where does the interstellar tunnel go?
The discovery of the tunnel brings to light a 1974 theory that states our galaxy has several interconnected hot bubbles and tunnels. However, there has never been any evidence that such a network exists.
Scientists believe the tunnel could be acting as a connector between the LHB and another superbubble or the Gum Nebula. The tunnel doesn't sit there all alone. The researchers' model showed that the northern region of the tunnel was hotter than the southern. This likely means that supernova events in the last few million years have likely reheated parts of the bubble.
The discovery of the tunnel towards Centaurus hints at the existence of a vast network of hot bubbles and tunnels in the Milky Way. These findings can help learn about the history of the galaxy, experts say.