Chinese astronomers discover nearest, lightest neutron star candidate

A group of Chinese astronomers identified a peculiar neutron star candidate in a binary system, 385 light years away from the Earth, which could be the nearest and lightest neutron star ever known if confirmed.

The researchers from Peking University and the National Astronomical Observatories under the Chinese Academy of Sciences reported the discovery based on observations of China's Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and the Nanshan 1-meter Wide-field Telescope (NOWT) in northwest China's Xinjiang Uygur Autonomous Region.

The candidate, a dark companion to an old-age star, with only approximately 0.98 times the solar mass, is presumed to resemble an X-ray-dim isolated neutron star (XDINS), but in binary, according to the study published in The Astrophysical Journal Letters.

To date, only seven XDINSs, peculiar objects with barely-detected radio signals, have been discovered. They are nicknamed the Magnificent Seven, about 391 to 1,630 light years away from the Earth.

The neutron stars are previously believed to have taken shape through the core-collapse supernovae, but they tend to be above 1.17 times solar mass.

LAMOST's spectral data also implied the presence of a small accretion disk around the neutron star candidate and/or a level of accretion disk activity, according to the study.

The new findings hinted at the radio-quite, XDINS-like compact object possibly being born in an alternative channel like the collapse of a white dwarf after it accretes, said the researchers.