Astronomers Discover Massive Metal Cloud Orbiting Unknown Planet

Astronomers have discovered a massive cloud of vaporized metals blocking the light of a distant star, and the cloud seems to be bound to an unknown object that could be either a large planet or a small star. This unusual find has offered scientists a rare opportunity to study the composition and movement of such a cloud in detail, reported Space.com.

The discovery came in September 2024, when a Sun-like star, J0705+0612, located about 3,000 light-years away, became 40 times less luminous than usual. The star dimmed for about nine months and returned to its normal brightness in May 2025.

Nadia Zakamska, an astronomer at Johns Hopkins, explained that such events are extremely rare. "Sun-like stars don't suddenly stop shining without reason, so such sudden dimming events are rare," she said.

Zakamska and her team observed the star with several telescopes, including the Gemini South Telescope (Chile), the Apache Point 3.5-meter Telescope, and the 6.5-meter Magellan Telescopes. Combining new observations with old data, they found that the star's light was temporarily blocked by a massive, slowly rotating cloud of gas and dust.

The estimated size of this cloud is about 120 million miles (200 million kilometers), which is about 15,000 times the diameter of Earth. It was about 1.2 billion miles (2 billion kilometers) away from the star when it dimmed the star's brightness, which is about 13 times the distance between Earth and the Sun.

The researchers also found that the cloud is bound by the gravity of another object orbiting the star. This object must be heavy enough to hold the cloud together, at least several times the mass of Jupiter. Scientists couldn't decide whether it was an asteroid, which would be called a circumsecondary disk, or a giant planet, which would be called a circumplanetary disk. It's extremely rare to see such a cloud transiting in front of a star.

The team used the Gemini High-Resolution Optical Spectrograph (GHOST) to determine the cloud's chemical composition. Zakamska said they had hoped to determine the cloud's chemical composition through spectroscopic observations, but the results exceeded all expectations.

The analysis revealed that the cloud contains elements heavier than hydrogen and helium, known as "metals" in astronomy. These included iron and calcium. The winds of these gases were measured in three dimensions, marking the first time the speed of gas in a disk orbiting a planet or a small star has been measured.

Zakamska explained that GHOST's sensitivity allowed them not only to detect the gas, but also to measure its movement. "This is something we've never been able to do before in a system like this," she said.

Analysis of the wind speed and direction revealed that the cloud is moving at a different speed from its host star, confirming that it is bound to an external secondary object. Researchers believe the cloud may have formed when two planets around the star collided, sending dust, rock, and debris into space. While such events are common in young planetary systems, this is unusual because this system is estimated to be about 2 billion years old.