[Gideon7]

This is called the Tolman–Oppenheimer–Volkoff limit, named after the three physicists who first calculated it in the 1930s. They came up with a value between 1.5 and 3 solar masses.

In 2007 a pular with 2.01 solar masses was found, which set a new lower limit. Then some researchers in 2017 set a new upper limit of 2.17, which I think is what the article might be talking about.

https://en.m.wikipedia.org/wiki/Tolman–Oppenheimer–Volkoff_limit

This figure is for the residual mass. About 90% of the original mass gets blown into space.

[Red Badger]

So it’s about 2.1 solar masses?............