What lies between the stars? Astronomers map a mysterious ‘interstellar tunnel' of plasma stretching from our solar system to distant stars

Time of India

9 hours ago

Astronomers have discovered evidence of a strange 'interstellar tunnel', a channel of hot, low-density plasma stretching out from our solar system toward distant stars. The finding, made using the
eRosita X-ray telescope
, sheds new light on the hidden structures of our galactic neighborhood and challenges long-held assumptions about the emptiness of space.
For decades, the general conception among scientists has been that the
Sun
sits inside a peculiar region called the
Local Hot Bubble
, a vast cavity about 300 light-years across, created by ancient
supernova explosions
.
These blasts heated the surrounding gas and carved out a bubble of hot, thin plasma. Until now, it was thought of largely as an isolated feature.
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This analysis, led by Dr. L. L. Sala and colleagues from the
Max Planck Institute
and published in Astronomy & Astrophysics, shows the bubble may be more connected than previously believed. Data reveal a tunnel-like structure extending toward the Centaurus constellation, and possibly another pathway leading toward Canis Major.
Mapping space with X-rays
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The breakthrough came from the eRosita X-ray telescope, part of the Spectrum-Roentgen-Gamma mission. It captured faint X-ray emissions from hot gas, then astronomers combined eRosita's results with older ROSAT data to map temperature differences and structures around the solar system.
Their painstaking survey divided the sky into thousands of sections, extracting signals from warm gas and dust cavities.
This revealed the faint glow of the Local Hot Bubble, and, unexpectedly, the presence of tunnel-like channels branching outward.
Old theories, new evidence
The idea of cosmic 'backroads', channels connecting regions of hot, thin gas, was suggested decades ago. However, evidence was lacking.
The new findings confirm at least part of those earlier theories, showing that supernova explosions may have left behind a patchwork of linked cavities that shape how energy and matter flow through the Milky Way.
What these tunnels could mean
The tunnels are not literal passageways, but low-density corridors in space where hot plasma has carved paths between star-forming regions. These features help explain how stellar winds, dust, and cosmic rays travel across the galaxy.
The study also found that the thermal pressure inside the Local Hot Bubble is lower than expected, which means the bubble might be open-ended in some directions, allowing these interstellar 'channels' to extend further.
Are spaces really void?
It is easy to picture space as empty, but that idea is misleading. The regions between stars are far from a perfect vacuum; they are filled with gas, dust, plasma, radiation, and magnetic fields. The Local Hot Bubble, the vast cavity surrounding our solar system, is a striking example of how violent events like supernovas can sculpt this interstellar material into surprising forms.
When stars explode, they blast out matter and energy that heat and churn the medium around them. Over millions of years, these forces create stark differences in density, temperature, and composition. What looks like a void is, in reality, a complex and dynamic environment.
The new study from the Max Planck Institute suggests that the bubble's internal pressure is lower than once thought, hinting that it may be open in certain directions. That could explain the tunnel-like channels of hot plasma extending toward distant constellations.
Still, much remains uncertain. Some regions appear to form continuous chains of cavities, while others are closed off. Understanding these tangled structures will require sharper data and more advanced models.
What is clear is that appearances deceive: space may look calm, but it carries the scars of ancient stellar upheavals.
Our solar system wandered into the Local Hot Bubble a few million years ago, long after nearby stars had exploded. Now we find ourselves near its center, not by design, but by coincidence.
It is as if we stumbled into the aftermath of a great cosmic event, arriving late to a party whose fireworks ended millions of years before humanity even existed.
What comes next
Researchers say more sensitive X-ray missions and 3D mapping will be needed to understand these structures fully.
Future work may reveal how widespread such tunnels are, how they influence galactic dynamics, and whether they connect into a larger network of super bubbles across the Milky Way.