Local Bubble

We live in a big space bubble.

This bubble is a very empty place. It has very little gas inside. Big stars exploded to make it. These explosions cleared the space out.

Our Sun travels through this bubble. It has been here for a long time. We are in a small cloud of gas. This cloud is inside the bubble.

As the bubble grows, it pushes gas. This gas clumps together. It helps make new stars.

Space is full of many bubbles. Some are near our bubble. It is a busy place in the sky.

We live inside a giant space bubble. Scientists call this the Local Bubble.

This bubble is a very empty place. It is filled with very little gas. It is at least 1,000 light years wide. The gas is much thinner than in other parts of our galaxy.

What made this bubble? Huge stars exploded in the past. These explosions are called supernovae. Many supernovae happened millions of years ago. They cleared the space out and made this cavity. Some scientists think groups of stars called LCC and UCL made it. These stars caused 14 to 20 supernovae.

Our Sun travels through this region. We have been here for five to ten million years. We are currently in a small cloud of gas. This is the Local Interstellar Cloud. It sits inside the larger bubble.

The bubble is not a perfect ball. It looks more like an egg. It might even look like an hourglass shape. As the bubble grows, it pushes gas and dust. This pushed material clumps together. This process helps make new, young stars nearby.

The Local Bubble is a huge, empty space in our galaxy. It is a cavity in the interstellar medium, which is the gas between stars.

This bubble is at least 1,000 light years wide. It is much thinner than other parts of the Milky Way. The gas density here is only 0.05 atoms per cubic centimeter. That is ten times less than the average density in our galaxy. Our Solar System is currently inside this bubble. We are moving through a small, denser area called the Local Interstellar Cloud.

Many things happened to create this empty space. Huge star explosions called supernovae cleared the gas away. These explosions happened between ten and twenty million years ago. Some scientists think the bubble came from the Pleiades moving group. Others believe two groups called LCC and UCL were responsible. These groups may have caused 14 to 20 supernovae.

These explosions created a remnant supershell. This shell pushed the gas out to make the bubble. The bubble is not a perfect sphere. It looks more like an egg or an hourglass shape.

Researchers have used many tools to study this region. A space observatory called CHIPSat looked at hot gas from 2003 to 2008. Another mission called the Extreme Ultraviolet Explorer studied it from 1992 to 2001. In 2019, scientists made the first 3D map of the bubble. They used observations of diffuse interstellar bands for this map. In 2020, they used 3D maps of dust to model its shape. These tools help us see how the bubble looks in deep space. It is exciting to see how our neighborhood is shaped.

We can find clues about these explosions right here on Earth. Scientists found interstellar iron in Antarctica in 2019. This iron might be linked to the Local Interstellar Cloud. We also find radioactive isotopes in deep-sea mud and lunar soil. One common isotope is iron-60. There are peaks of iron-60 from millions of years ago. One peak happened 4.5 million years ago when we entered the bubble. Another peak happened between 1.7 and 3.2 million years ago. These tiny pieces of metal tell the story of ancient star deaths.

This bubble does more than just sit in space. As the bubble expands, it pushes gas and dust outward. This moving edge sweeps up material like a snowplow. The gas and debris clump together on the bubble's surface. This helps form new, young stars in places like the Taurus molecular cloud.

The bubble also touches other bubbles, like the Loop I Bubble. A path called the Lupus Tunnel connects these two cavities. Understanding the bubble helps us see how stars are born. It shows us how one event can change a whole part of space.

The Local Bubble is a vast, low-density cavity within the interstellar medium (ISM) of the Milky Way. The interstellar medium refers to the gas and dust that exists in the spaces between stars. Located in the Orion Arm, this bubble contains many of our closest neighbors, including stars and brown dwarfs. It also houses the Local Interstellar Cloud, which contains our own Solar System.

This region is significant because it defines our immediate galactic neighborhood. By studying it, astronomers can understand how massive stellar events shape the structure of our galaxy.

This enormous cavity was created by the energy of multiple supernovae. A supernova is the powerful explosion of a star. These explosions occurred within the last ten to twenty million years. As these stars exploded, they pushed the surrounding gas outward. This process created a remnant supershell of material. Some researchers believe the Pleiades moving group caused these explosions. Other studies suggest the Scorpius–Centaurus association was the source. Specifically, the subgroups Lower Centaurus–Crux (LCC) and Upper Centaurus–Lupus (UCL) may have been responsible. It is estimated that between 14 and 20 supernovae originated from these groups to form the bubble.

The Local Bubble is not a perfect sphere. Its shape is more complex and varies depending on its location. It appears narrower within the galactic plane. In other areas, it may look like an egg or an ellipse. Above and below the galactic plane, it might widen into an hourglass shape. The bubble also interacts with other nearby cavities. One major neighbor is the Loop I Bubble, which was created by the Scorpius–Centaurus association about 500 light years away. A specific connection called the "Lupus Tunnel" links the Local Bubble to the Loop I Bubble.

Scientists have used several advanced missions to map this region. The Extreme Ultraviolet Explorer operated from 1992 to 2001 to study hot EUV sources. Later, the Cosmic Hot Interstellar Plasma Spectrometer (CHIPSat) examined hot gas from 2003 to 2008. In 2019, researchers achieved a major milestone by creating the first 3D map of the Local Bubble. They did this using observations of diffuse interstellar bands. By 2020, scientists used 3D dust density maps to model the dusty envelope surrounding the bubble. These tools allow us to visualize a structure that is otherwise difficult to see.

The scale of the Local Bubble is immense. It is estimated to be at least 1,000 light years in size. The density of gas inside the bubble is very low. It measures about 0.05 atoms per cubic centimeter. This is only about one tenth of the average density found in the Milky Way's interstellar medium. For comparison, the Local Interstellar Cloud has a density of 0.3 atoms per cubic centimeter. This makes the cloud about six times denser than the bubble itself.

The expansion of the bubble has a direct impact on the birth of stars. As the bubble expands, its surface sweeps up interstellar gas and dust. This material collects and collapses on the outer edge of the bubble. This process is responsible for the formation of all young, nearby stars. Examples of these stars can be found in molecular clouds like the Taurus molecular cloud. The Pleiades open cluster is another example of stars formed this way.

We can find physical evidence of these ancient explosions right here on Earth. Radioactive isotopes provide a historical record of nearby supernovae. Scientists study these in deep-sea ferromanganese crusts, Antarctic snow, and lunar soil. Iron-60 is a common isotope used to track these events. There is a notable peak of iron-60 from 4.5 million years ago. This likely occurred when our Solar System entered the Local Bubble. Another peak occurred between 1.7 and 3.2 million years ago. In 2019, researchers even found interstellar iron in Antarctica that may relate to the Local Interstellar Cloud. These tiny particles allow us to trace the history of our galaxy through time.