A Sun-like star 3,000 light-years away abruptly dimmed for nine months, revealing a colossal cloud of gas and dust likely from a planetary collision. Astronomers used advanced telescopes to measure metallic winds within the cloud for the first time. The event highlights ongoing chaos in ancient star systems.
In September 2024, the star J0705+0612, which resembles our Sun, suddenly dimmed to just one-fortieth of its normal brightness, an event that lasted until May 2025. Located about 3,000 light-years from Earth, this dramatic change puzzled astronomers, as such dimming is rare for stable stars like this one.
"Stars like the Sun don't just stop shining for no reason," said Nadia Zakamska, a professor of astrophysics at Johns Hopkins University. "So dramatic dimming events like this are very rare."
Zakamska and her team launched an observing campaign using the Gemini South telescope in Chile, the Apache Point Observatory's 3.5-meter telescope, and the Magellan Telescopes. Their analysis, published in The Astronomical Journal, indicated the star was obscured by a vast cloud of gas and dust, positioned about two billion kilometers from the star and spanning 200 million kilometers across.
The cloud appears bound to a massive companion object orbiting the star, with a mass of at least several Jupiters. This companion could be a giant planet, brown dwarf, or low-mass star. Archival data revealed similar dimmings in 1937 and 1981, suggesting a 44-year orbital period.
In March 2025, the team employed Gemini South's GHOST instrument to spectroscopically analyze the cloud during the occultation. The observations detected gaseous metals like iron and calcium, and for the first time, measured three-dimensional gas motions within a circumsecondary or circumplanetary disk.
"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."
The star, aged over two billion years, shows excess infrared suggesting a debris disk not from its formation but possibly from a recent planetary collision. "This event shows us that even in mature planetary systems, dramatic, large-scale collisions can still occur," Zakamska noted. "It's a vivid reminder that the Universe is far from static."
This discovery underscores the power of new instruments in probing transient events in distant systems.