Two's company: Scientists identify new class of star remnants

In about 5 to 8 billion years, our Sun is expected to evolve into a white dwarf, an extremely dense stellar remnant about the size of Earth that has exhausted its fuel and lost its outer layer. But even though our Sun is a lone star, research over the past 15 years has demonstrated that binary or multi-star systems are far more common than astronomers once thought. When a dense, compact remnant like a white dwarf is involved in a binary system, it often “rips” material from its companion star. This process, called accretion, typically emits X-rays in what is considered a “signature” signal.