A hidden molecular cloud near our Milky Way’s center

A hidden molecular cloud in our Milky Way

Our Milky Way galaxy consists of gas, dust and billions of stars. They trace out its spiral arms and form its central bulge, while a supermassive black hole resides at our galaxy’s center. But on July 16, 2025, astronomers from the National Science Foundation’s National Radio Astronomy Observatory said they’ve found a giant molecular cloud – a gaseous region of star birth made mostly of molecular hydrogen – that was previously hidden from our view. The molecular cloud lies at a transition zone between the quieter galactic disk and the more extreme central region.

Lead author Natalie Butterfield of the NSF National Radio Astronomy Observatory said:

One of the big discoveries of the paper was the giant molecular cloud itself. No one had any idea this cloud existed until we looked at this location in the sky and found the dense gas. Through measurements of the size, mass and density, we confirmed this was a giant molecular cloud.

The Midpoint Cloud

The scientists have dubbed their new discovery the Midpoint Cloud. That’s because it was found at the midpoint of the dust lanes in the central bar in our galaxy. This active region is likely the location of new star birth. Butterfield described the molecular cloud in detail:

These dust lanes are like hidden rivers of gas and dust that are carrying material into the center of our galaxy. The Midpoint cloud is a place where material from the galaxy’s disk is transitioning into the more extreme environment of the galactic center. It provides a unique opportunity to study the initial gas conditions before accumulating in the center of our galaxy.

The astronomers used the Green Bank Telescope in West Virginia to make their discovery. They looked at molecules such as ammonia and cyanobutadiyne (which has hydrogen, carbon and nitrogen atoms). These molecules help trace out the dense gas.

The researchers said the Midpoint Cloud is likely a “crucial link” in how material flows to the center of the galaxy. Studying this cloud might reveal the process of galaxies building their central structures. And it should show how stars form in extreme environments.

Other discoveries

The researchers outlined other discoveries in their paper. They found a new maser, which stands for microwave amplification by stimulated emission of radiation (like laser but for microwave light). The maser could be a sign of star formation.

Other signs of star birth include clumps of gas and dust that the astronomers said might be forming new stars. But some of the new stars are eating away at other clumps. For example, the researchers named one clump Knot E. It appears this dense little knot of dust is eroding due to surrounding stars.

And the cloud is home to not just star birth, but stars dying as well. Researchers found a shell that’s likely the remains of a dying star. In general, there’s a lot going on in this chaotic cloud. Co-author Larry Morgan of the NSF Green Bank Observatory said:

Star formation in galactic bars is a bit of a puzzle. The strong forces in these regions can actually suppress star formation. However, the leading edges of these bars, such as where the Midpoint is located, can accumulate dense gas and trigger new star formation.

Bottom line: Researchers have discovered a giant molecular cloud that has been hiding in our Milky Way galaxy near its central bar. The area is likely a region of star birth.

Source: Discovery of a Giant Molecular Cloud at the Midpoint of the Galactic Bar Dust Lanes: M4.7–0.8

Via NRAO

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