2026ApJ...998...78G

Quasiperiodic eruptions (QPEs), the repeated outbursts observed in soft X-ray bands, have attracted broad interest, but their physical origin is under debate. One of the popular models, the star-disk collision model, suggests that QPEs can be produced through periodic collisions of an orbiting star with the accretion disk of a central black hole (BH). However, previous tests of the star-disk collision model mainly focus on the timing analysis. Other observed properties, such as peak luminosities L_p, durations t_e, and radiation temperatures T_p of the eruptions, are not systematically investigated. For a sample of six QPE sources and two QPE-like sources, we test the shock-cooling emission model from star-disk collisions by using these observables to derive the constraints on the stellar radius R_⋆. We find that, except for two sources (eRO-QPE3 and eRO-QPE4), the rest of the sample either has no allowed R_⋆ to simultaneously reproduce the observed L_p and t_e or the required R_⋆ is too large to avoid being disrupted by the central BH. For the two exceptions, a stellar radius of the order of 1 R_⊙ is necessary to satisfy all the constraints. Another issue with the simplest version of this model is that it predicts kT_p ∼ 10 eV, one order of magnitude lower than the observed value.