Stability of mini-boson stars

A mini-boson star refers to a bound system of a complex scalar boson field with an astronomically large particle number N, but only a very small stellar radius ≅ Compton wavelength of a free boson, m-1. The star is held together by gravity. We prove that the lowest mass 1s solutions are stable against small oscillations, whereas other ns solutions (n≥2) are not. Thus, the critical mass of mini-boson stars is the Kaup-Ruffini-Bonazzola limit M≅0.633(Gm)-1 where G is Newton's constant. (orig.)