Sweeping winds of vaporized metals have been detected in a massive cloud that dimmed the light of a distant star for nearly nine months. This groundbreaking discovery, made using the Gemini South telescope in Chile, part of the International Gemini Observatory, offers a rare insight into the chaotic processes still shaping planetary systems long after their formation.
In September 2024, a star located 3,000 light-years away, known as J0705+0612, suddenly became 40 times dimmer than usual and remained so until May 2025. The star, similar to our Sun, caught the attention of Nadia Zakamska, a professor of astrophysics at Johns Hopkins University. Zakamska remarked, “Stars like the Sun don’t just stop shining for no reason, so dramatic dimming events like this are very rare.”
Unveiling the Mystery: Observations and Findings
Recognizing the opportunity to study this rare event, Zakamska and her team initiated observations using the Gemini South telescope, along with the Apache Point Observatory and the Magellan Telescopes. Their findings, published in The Astronomical Journal, revealed that the star had been occulted by a vast, slow-moving cloud of gas and dust. This cloud is estimated to be about two billion kilometers from its host star and roughly 200 million kilometers in diameter.
The data suggest that this cloud is gravitationally bound to a secondary object orbiting the star in the outer reaches of its planetary system. While the nature of this object remains unknown, it must be massive enough to hold the cloud together, with possibilities ranging from a planet to a brown dwarf or an extremely low-mass star.
Technological Breakthrough: GHOST Instrument
To investigate the cloud’s composition, the team employed the Gemini High-resolution Optical SpecTrograph (GHOST). In March 2025, GHOST observed the occultation for over two hours, dispersing the star’s light into a spectrum that revealed the chemical elements present in the cloud.
“When I started observing the occultation with spectroscopy, I was hoping to unveil something about the chemical composition of the cloud, as no such measurements had been done before. But the result exceeded all my expectations,” Zakamska stated.
The GHOST data revealed multiple metals — elements heavier than helium — within the cloud. More remarkably, the high precision of the spectra allowed the team to directly measure how the gas is moving in three dimensions.
Implications for Understanding Planetary Systems
The discovery of metallic winds in the cloud marks the first time astronomers have measured the internal gas motions of a disk orbiting a secondary object. This dynamic environment, with winds of gaseous metals like iron and calcium, provides new insights into the long-term evolution of planetary systems.
“The sensitivity of GHOST allowed us to not only detect the gas in this cloud, but to actually measure how it is moving,” Zakamska explained. “That’s something we’ve never been able to do before in a system like this.”
Chris Davis, NSF Program Director for NOIRLab, noted, “This study illustrates the considerable power of Gemini’s newest facility instrument, GHOST, and further highlights one of Gemini’s great strengths — rapidly responding to transient events like this occultation.”
Origins and Future Research
The source of the cloud shows infrared excess, typically associated with disks around young stars. However, J0705+0612 is over two billion years old, suggesting the disk is unlikely to be leftover debris from the system’s early planet formation stage. Zakamska proposes that it originated after two planets collided in the outer reaches of the star’s planetary system, ejecting dust, rocks, and debris to form the massive cloud.
This discovery emphasizes how new technology enables further understanding of the Universe. GHOST has opened a new window into studying hidden phenomena in distant star systems, offering valuable clues about how disks can form around old stars.
“This event shows us that even in mature planetary systems, dramatic, large-scale collisions can still occur,” says Zakamska. “It’s a vivid reminder that the Universe is far from static — it’s an ongoing story of creation, destruction, and transformation.”
The research, titled “ASASSN-24fw: Candidate Gas-rich Circumsecondary Disk Occultation of a Main-sequence Star,” involves a team of international scientists and highlights the collaborative nature of astronomical research. The findings not only deepen our understanding of cosmic phenomena but also pave the way for future studies of similar events in the Universe.
