NICER / ISS Science Nugget for April 26, 2018
Pulsar and orbital periodicities discovered in IGR J17062-6143
NICER's fourth peer-reviewed paper was accepted for publication this week: Strohmayer et al., "NICER Discovers the Ultracompact Orbit of the Accreting Millisecond Pulsar IGR J17062-6143," in The Astrophysical Journal Letters.
NICER observations of this accreting millisecond X-ray pulsar (AMXP) clearly detected 163 Hz pulsations (figure, upper-left panel) from the neutron star in this binary system, confirming a past hint of these pulses seen with an earlier X-ray telescope. Data spanning several months were accumulated with NICER; they showed that the pulsations arrive at the telescope systematically early or late depending on the neutron star's orbital motion in the binary (figure, lower-left panel).
Analysis of the NICER dataset revealed that the binary is the most compact AMXP known, with an orbital period of just 38 minutes. NICER data show that the system comprises a neutron star and a very low-mass (< 0.015 Solar mass) white dwarf companion separated by only 300,000 km, less than the Earth-to-Moon distance.