One Star Is Orbiting Inside Another in This Never-Before-Seen Binary System

For the first time, astronomers have spotted a rapidly spinning neutron star that is gravitationally bound to a helium star companion. The discovery of this unusual binary system helps confirm a long theorized—but rarely seen—cosmic process called common envelope evolution. Binary star systems, or pairs of stars that orbit around each other, are very common. In fact, it’s estimated that 85% of stars in the universe have at least one companion. But this newly discovered pair is unlike any seen before. In this case, a helium star is bound to a millisecond pulsar: a fast-spinning neutron star that emits beams of radiation at regular intervals. These stars achieve their extraordinary rotation rates by siphoning matter from nearby stellar companions. In May 2020, a team of researchers led by Jin Lin Han, a radio astronomer at the National Astronomical Observatories and the Chinese Academy of Sciences in Beijing, used China’s FAST radio telescope to detect weak signals from a point deep w ... Read full article.