After making an educated guess of the mass of the visible companion from the correlation of the luminosity, mass, and temperature for normal stars, the rest of the total mass is the unseen object's mass.
(the rest of the total mass; is; the unseen object's mass; T:After making an educated guess of the mass of the visible companion from the correlation of the luminosity, mass, and temperature for normal stars)
the rest of the total mass
is
the unseen object's mass T:After making an educated guess of the mass of the visible companion from the correlation of the luminosity, mass, and temperature for normal stars