Samar Safi-Harb

North of the microquasar SS 433, an arc has emerged in the soft X-ray band. Faint and diffuse, yet stubbornly tracing contours already familiar from radio observations. Astronomers studied its spectrum and saw gas heated to eleven million kelvin. Gas that could not have been heated by the jets or the accretion disk wind.

Deep inside a massive star, before it explodes, layers sit on top of each other like the layers of an onion. Sometimes two adjacent layers, the carbon and oxygen layers, mix together. It's like how layers of broth and vegetables in a pot of soup blend when you stir them with a spoon.

Seventeen minutes: that’s the heartbeat frequency of AM Canum Venaticorum, setting the rhythm for the entire class of ultracompact binaries. In these systems, two white dwarfs whirl in a death dance, tightening their orbit to the still-inaudible whisper of gravitational waves.