A team of researchers investigating a star\u2019s dramatic dimming uncovered a cloud of dust and gas about 120 million miles (200 million kilometers) wide. Exactly what caused the cloud to form, and the nature of its host object, remain unknown.<\/p>\n
From September 2024 to May 2025, a Sun-like star designated J0705+0612 became 40 times dimmer. Researchers describe the phenomenon in a study<\/a> published today in The Astronomical Journal, identifying the culprit as a slowly orbiting giant cloud.<\/p>\n \u201cStars like the Sun don\u2019t just stop shining for no reason,\u201d Nadia Zakamska, a Johns Hopkins University professor of astrophysics and co-author of the study, said in a NOIRLab statement<\/a>, \u201cso dramatic dimming events like this are very rare.\u201d<\/p>\n A pesky cloud <\/p>\n In this case, Zakamska and her colleagues integrated telescopic observations with the star\u2019s archival data and concluded that a cloud of dust and gas had, for a while, obscured the star. According to their estimates, the distance between this feature and the star is about 1.2 billion miles (2 billion kilometers). The star is located 3,000 light-years from Earth.<\/p>\n Cue a mysterious third player: a gravitational tie seems to link the cloud to another body at the edge of J0705+0612\u2019s planetary system. Researchers don\u2019t yet know what this body is. It orbits J0705+0612 and needs to have enough mass to keep the cloud from coming apart. According to their findings, it must consist of a few Jupiter masses\u2014at least. A very large exoplanet, a brown dwarf, or a very low-mass star are potential candidates.<\/p>\n If the body is a star, the cloud would be a circumsecondary disk\u2014a frisbee of debris orbiting the less massive companion in a binary system. If it\u2019s a planet, the cloud would be a circumplanetary disk. More broadly, it\u2019s rare for researchers to observe a star being obscured directly by the disk of a secondary object.<\/p>\n What\u2019s in the cloud? <\/p>\n \u201cWhen 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,\u201d says Zakamska.<\/p>\n