Caleb et al. have reported the discovery of the source ASKAP J1935+2148, which is likely to be a neutron star spinning slower than any other ever measured. At the end of their life, large stars about 10 times the mass of the Sun use up all their fuel and explode in a supernova. What remains is a stellar remnant so dense that 1.4 times the mass of our Sun is packed into a ball just 20 kilometres across. Matter is so dense that negatively charged electrons are crushed into positively charged protons and what’s left is an object made up of neutrally charged particles — a neutron star. The neutron stars are generally spinning rapidly, taking just seconds or even fractions of a second to rotate.

ASKAP J1935+2148, which was serendipitously discovered during a target of opportunity observation of the gamma-ray burst GRB 221009A, emits pulses with a comparatively leisurely period just shy of one hour. No other radio-emitting neutron star, out of the more than 3000 discovered so far, has been discovered rotating so slowly. The origin of such a long period signal remains a profound mystery, although two types of stars are prime suspects – white dwarfs and neutron stars. More research will be required to confirm whether the object is a neutron star or white dwarf. Either way, it will provide valuable insights into the physics of these extreme objects. The image above is an artist’s depiction of the ASKAP radio telescope with two versions of the mysterious celestial object: neutron star and white dwarf. (Image credit: Carl Knox/OzGrav)

As Monday June 10th is a public holiday, the next ADAP will be Tuesday June 11th