The heaviest neutron star on record is 2.35 times the mass of the sun

The record breaker owes its massive success to infalling gas from a companion star

illustration of a neutron star that became a pulsar next to an orbiting star

So much gas from an orbiting star (illustrated in orange) fell onto this neutron star (white with green and purple beams) that it began to spin fast, becoming a pulsar, and also grew to a record-breaking mass.

Cruz deWilde/NASA Goddard Space Flight Center

A fast-spinning neutron star south of the constellation Leo is the most massive of its kind seen so far, according to new observations.