Researchers at Oxford University and the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) are proposing a new way to observe tightly bound supermassive black hole binaries. Formed naturally when galaxies merge, only widely separated systems have confidently been observed to date. In a paper published today in Physical Review Letters, the researchers suggest hunting down the hidden systems by searching for repeating flashes of light from individual stars lying behind the black holes as they are temporarily magnified by gravitational lensing as the binary orbits. 

A new study suggests that dark matter may consist of particles with different masses. By introducing a two-component self-interacting dark matter model, the researchers show that both the low-density cores of dwarf galaxies and the unexpectedly dense substructures seen in strong gravitational lensing can be explained within a single framework, offering new insight into the nature of dark matter.

One of the longest stellar dimming events ever observed was likely caused by the gigantic saucer-like rings of either an unseen brown dwarf or 'super-Jupiter' blocking its host star's light, astronomers say. For decades the star – which sits 3,200 light-years from Earth and is about twice as big as our Sun – had been observed as stable, but at the end of 2024 it faded dramatically. It then remained this way for more than nine months, far longer than is normal for an event like this, sparking confusion among researchers and prompting speculation as to what could have caused such an "extremely rare" phenomenon. Now, in a new study published today in Monthly Notices of the Royal Astronomical Society, a team of international researchers believe they may have solved the riddle of this mysterious star in the Monoceros constellation.

Recent research suggests that Saturn’s bright rings and its largest moon, Titan, may have both originated in collisions among its moons. While Cassini’s 13-year mission expanded our understanding of Saturn, the discoveries of its young rings and Titan’s rapidly shifting orbit raised new questions. Now, a study led by SETI Institute scientist Matija Ćuk proposes an explanation linking the formation of the moons and rings, centering on the possibility that Titan is the product of a moon merger.

Near the end of its mission, Cassini measured Saturn’s internal mass distribution, which governs the planet’s slow spin-axis wobble, or precession. For decades, scientists thought Saturn’s precession period matched Neptune’s, enabling the two planets’ gravitational interactions to gradually tilt Saturn and let us clearly see its rings. Cassini’s final trajectory showed Saturn’s mass is slightly more concentrated at its center than expected, changing its precession rate so it no longer matches Neptune’s. To explain this, researchers at MIT and UC Berkeley proposed that Saturn once had an extra moon, which was ejected after a close encounter with Titan and broke up to form the rings.

USA: What appears to be a single volcanic eruption is often the result of complex processes operating deep beneath the surface, where magma moves, evolves, and changes over long periods of time. To fully understand how volcanoes work, scientists study the volcanic products that erupt at the surface, which can reveal the hidden magmatic systems feeding volcanic activity. New research published recently in Geology shows that this complexity also applies to Mars.