The most massive neutron star discovered to date is a pulsar named J0740+6620. It was announced in 2019 and is located around 4,600 light-years away from Earth in the constellation Camelopardalis. The mass of J0740+6620 has been measured to be approximately 2.14 times the mass of the Sun, making it one of the most massive known neutron stars.
Neutron stars are incredibly dense remnants of massive stars that have undergone supernova explosions. They consist primarily of tightly packed neutrons and are typically only about 10-20 kilometers (6-12 miles) in diameter. Due to their extreme densities, neutron stars have extremely strong gravitational fields.
It's worth noting that our understanding of neutron stars is continuously evolving as new observations and measurements are made. As technology advances and more data is gathered, it is possible that even more massive neutron stars will be discovered in the future.