NICER Finds X-ray Pulsar in Record-fast Orbit

Scientists analyzing the first data from the Neutron Star Interior Composition Explorer (NICER) mission have found two stars that revolve around each other every 38 minutes. One of the stars in the system, called IGR J17062–6143 (J17062 for short), is a rapidly spinning, superdense star called a pulsar. The discovery bestows the stellar pair with the record for the shortest-known orbital period for a certain class of pulsar binary system.

The data from NICER also show J17062’s stars are only about 186,000 miles (300,000 kilometers) apart, less than the distance between Earth and the Moon. Based on the pair’s breakneck orbital period and separation, scientists involved in a new study of the system think the second star is a hydrogen-poor white dwarf.

The researchers were also able to determine that J17062’s stars revolve around each other in a circular orbit, which is common for this type of system. The white dwarf donor star is a “lightweight,” only around 1.5 percent of our Sun’s mass. The pulsar is much heavier, around 1.4 solar masses. The stars orbit a point around 1,900 miles (3,000 km) from the pulsar, almost as if the donor star orbits a stationary neutron star, but NICER can is sensitive enough to detect a slight fluctuation in the neutron star’s X-ray emission due to the tug from the donor star.

See NASA.gov