Daichi Hiramatsu

The binary system SS 433 ejects two thin jets of gas at nearly the speed of light. One flies toward us, the other away from us. In April 2024 and March 2025, three instruments watched them simultaneously: the X-ray telescope XRISM, ordinary optical telescopes, and a near-infrared camera.

A light bulb that doesn't burn out but flares brighter and brighter until it blows the whole fixture apart. That's roughly how the most massive stars in the universe die. When a star's core heats up to billions of degrees, pairs of particles (electrons and their antimatter counterparts, positrons) begin to form.

On August 6, 1181, Chinese astronomers spotted a new star in the constellation Cassiopeia. It shone for 185 days, slowly fading, and then vanished, leaving only a record in the chronicles. Today, at its location, there is a hot white dwarf — a compressed stellar core with no nuclear reactions, heated to tens of thousands of degrees.