Astronomers have finally uncovered the nature of a mysterious object that for nearly four decades was thought to be a giant structure rising above the center of our galaxy. It turns out that the famous Galactic Center Lobe (GCL) is not actually connected to the Milky Way's core and is located significantly closer to Earth.

What was previously thought

Since its discovery in the 1980s, scientists debated the origin of the GCL. Some believed it to be a remnant of an ancient outflow from the supermassive black hole at the galaxy's center, while others linked the object to supernova explosions. Due to the many conflicting hypotheses, the GCL was even called a "Rorschach test for galactic astrophysics."

What has now been found

A new study, published in the journal Astronomy & Astrophysics (A&A), has completely overturned previous assumptions. Using data from the SDSS-V Local Volume Mapper survey, astronomers determined that the object is located just 6,520 light-years from Earth, rather than the 26,000 light-years previously thought.

Furthermore, the GCL turned out not to be a giant "lobe" but a closed loop about 115 light-years in diameter. The lower part of the structure had previously been hidden by dust and blended into the background of the Milky Way, creating the illusion of an open giant lobe. New observations in ionized sulfur emission lines allowed the object to be seen in its entirety.

What it is

According to the researchers, the loop is a giant bubble of hydrogen gas formed by the activity of massive stars. Previous generations of stars exploded as supernovae, creating a cavity in the interstellar medium, while the next generation of stars illuminated the surrounding gas with powerful ultraviolet radiation.

In brief

Astronomers have found that the mysterious "Galactic Center Lobe" (GCL), which for nearly 40 years was thought to be a structure at the center of the Milky Way, is actually located just 6,520 light-years from Earth and is a closed loop 115 light-years in diameter. The object turned out to be a bubble of hydrogen gas created by the activity of massive stars. The discovery has resolved one of the longest-standing mysteries of our galaxy and demonstrated just how deceptive observations can be, even in well-studied regions. The work was published in the journal Astronomy & Astrophysics.