Astronomy: The black hole GX 339-4, near the center of our galaxy, has a mass at least six times greater than our Sun and is orbited by a companion star that feeds it. Most of the material from the star is pulled into the black hole, but some of it is blasted outward at nearly the speed of light.Poshak Gandhi from the Japan Aerospace Exploration Agency and colleagues have used data from NASA’s Wide-Field Infrared Survey Explorer (WISE) to zoom in on the area around the base of the jet. They found that the jet’s base has an average radius of about 24 000 km and that it can fluctuate by at least a factor of 10. The jet’s activity also undergoes significant and dramatic fluctuations on time scales ranging from 11 seconds to a few hours. Their observations suggest GX 339-4’s magnetic field is 30 000 times more powerful than that of Earth. The field provides the black hole with the necessary force to accelerate and channel the flow of matter from its companion star into a jet.
The finding that the Saturnian moon may host layers of icy slush instead of a global ocean could change how planetary scientists think about other icy moons as well.
Modeling the shapes of tree branches, neurons, and blood vessels is a thorny problem, but researchers have just discovered that much of the math has already been done.
January 29, 2026 12:52 PM
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