Low-surface-brightness spheroidal galaxies as Milgromian isothermal
  spheres
  I consider a sample of eight pressure-supported low-surface brightness
galaxies in terms of Milgrom's modified Newtonian dynamics (MOND). These
objects include seven nearby dwarf spheroidal galaxies -- Sextans, Carina, Leo
II, Sculptor, Draco, Leo I, Fornax, and the ultra-diffuse galaxy DF44. The
objects are modelled as Milgromian isotropic isothermal spheres characterised
by two parameters that are constrained by observations: the constant
line-of-sight velocity dispersion and the central surface density. The velocity
dispersion determines the total mass, and, with the implied mass-to-light
ratio, the central surface brightness. This then specifies the radial run of
surface brightness over the entire isothermal sphere. For these objects the
predicted radial distribution of surface brightness is shown to be entirely
consistent with observations. This constitutes a success for MOND that is
independent of the reduced dynamical mass.
