Earlier this year, an international team of scientists announced the second detection of a gravitational-wave signal from the collision of two neutron stars. The event, called GW190425, is puzzling: The combined mass of the two neutron stars is greater than any other observed binary neutron star system. The combined mass is 3.4 times the mass of our sun.
Source:
https://phys.org/news/2020-05-scientists-puzzle-massive-never-before-seen-star.html