At INFN: On the radius

It's time to catch up with Physics. As Watts mentioned about mass measurements
Illarionov open his mouth and asked the uncomfortable question. What about radius? And he got to face the truth: that we don't have precise measurements at all. And it's because basically no optical telescope can resolve such a small, distant object. It has to be derived in an indirect way by any astrophysical process and since usually the radius comes together with the mass (compactness parameter: the mass to ratio quotient) the situation becomes hard. But there's a hope: gravitational waves. By measuring gravitational wave emissions from star oscillation is possible to get a good number for the radius. In contrast the mass values are well determined mainly by binary systems, as shown in this figure.