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The inset shows the planetary debris disk and its cloud of gas and dust passing in front of the star. |Image source: International Gemini Observatory/NOIRLab/NSF/AURA/P. Mullenfeld and M. Zamani
The giant clouds that block light from distant stars were discovered to consist of whirlwinds of vaporized metal. What’s even stranger is that the cloud seems to be strangely combined with a mysterious celestial body, which may be a giant planet or a low-mass star.
Astronomers first learned of the existence of such metallic clouds in September 2024, when a sun-like star cataloged as J0705+0612 located about 3,000 light-years away became 40 times dimmer than usual. This dimming lasted for nine months until the star returned to its original brightness in May 2025.
This dramatic dimming intrigued Johns Hopkins University astronomer Nadia Zakamska because astronomers don’t typically witness such events. “A star like this sun Don’t stop glowing for no reason, so dramatic dimming events like this are very rare,” Zakamska said in a statement.
Zakamska and colleagues used Gemini South Telescope, The 3.5-meter telescope and the 6.5-meter telescope at Cape Apache Observatory in Monte Pajon, Chile Magellan telescope. Combining these new observations of J0705+0612 with archival data, they found that the star is temporarily covered or obscured by large, slow-moving clouds of gas and dust.
The team estimates the cloud is about 120 million miles (200 million kilometers) wide, or about 15,000 times the diameter of Earth. It is estimated that J0705+0612 was about 1.2 billion miles (2 billion kilometers) away when it caused the star to dim. This is approximately 13 times the distance between the Earth and the Sun.
Low-mass stars or massive planets?
The researchers also discovered that the cloud is gravitationally bound to another celestial body, also orbiting the star J0705+0612. The object would have to be massive enough to create a strong enough gravitational influence to hold the cloud together, meaning it would have a mass of at least Jupiteralthough it could be much larger than that. That means the big question is: What is the nature of this mysterious object?
If the object is a star, then the cloud is a ring secondary disk, a cloud of gas and dust orbiting the less massive star in the binary system. If the unknown object is a planet, then the cloud is a circumplanetary disk. Observing either type of cloud obscuring a star is extremely rare.
To determine the cloud’s composition, the researchers used Gemini South’s Gemini High-Resolution Optical Spectrograph (GHOST) to observe the cloud in front of J0705+0612 for two hours.
“When I started looking at the occultation with a spectrometer, I hoped to reveal something about the chemical composition of the cloud, because no such measurements had been made before,” Zakamska said. “But the results exceeded all my expectations.”
The team found that the clouds are rich in elements heavier than hydrogen and helium, which astronomers somewhat confusingly call “metals.” These winds of gaseous metals, including iron and calcium, were mapped in three dimensions, marking the first time astronomers have measured the inner gas motions of a disk orbiting a secondary body such as a planet or a low-mass star.
“GHOST’s sensitivity allows us to not only detect the gas in the cloud but actually measure how it’s moving,” Zakamska said. “This is something we’ve never been able to do in a system like this before.”
Mapping the speed and direction of the wind within the cloud revealed to the team that it was moving separately from the primary star, further confirming that it is bound to a secondary object located at the outer boundary of the planetary system.
The team believes the cloud may have formed when two planets orbiting J0705+0612 collided with each other, spewing dust, rocks and other debris. Such events are common in chaotic and young planetary systems, but unusual for a system like this, which is estimated to be about 2 billion years old.
“This event shows us that violent, massive collisions can still occur even in mature planetary systems,” Zakamska said. “It’s a vivid reminder that the universe is far from static – it is an ongoing story of creation, destruction and transformation.”
The team’s findings were published in the journal on Wednesday (January 21) Journal of Astronomy.
