2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/11053Quasi-periodic brightness oscillations (QPOs) with frequencies in the range 300-1200 Hz have been detected from at least nine neutron star low-mass X-ray binaries. Here we summarize the sonic-point model for these brightness oscillations, which we present in detail elsewhere. If the sonic-point interpretation of kilohertz QPOs is confirmed, measurements of kilohertz QPO frequencies in low-mass X-ray binaries will provide new bounds on the masses and radii of neutron stars in these systems and new constraints on the equation of state of matter at high densities.3 pages LaTeX using sprocl.sty (available from ftp://ftp-astro-theory.fnal.gov/pub/Personal/texas/sprocl.sty), to appear in Proceedings of the 18th Texas Symposium on Relativistic Astrophysics (eds Olinto, Frieman and Schramm, World Scientific)Astrophysicstext