Magnetic signatures on mixed-mode frequencies

Context. The discovery of moderate differential rotation between the core and envelope evolved solar-like stars could be signature a strong magnetic field trapped inside radiative interior. population intermediate-mass red giants presenting surprisingly low-amplitude mixed modes (i.e. oscillation that behave as acoustic in their external gravity core) also arise from effect an internal field. Indeed, more massive than about 1.1 solar masses are known to develop convective during main sequence. generated by dynamo triggered this convection progenitor fossil star for remainder its evolution. Aims. Observations can constitute excellent probe deepest layers stars, fields those regions impact propagation. perturbation on may therefore visible asteroseismic data. To unravel which constraints obtained observations, we theoretically investigate effects plausible axisymmetric with various amplitudes mixed-mode frequencies stars. Methods. First-order frequency perturbations due were computed dipolar quadrupolar modes. These computations carried out range stellar ages, masses, metallicities. Conclusions. We show typical fossil-field strengths 0.1 − 1 MG, consistent presence sequence, provoke significant asymmetries multiplets giant branch. provide methods detectability such signatures. these signatures detectable data small enough amplitude not affected conversion into Alfvén waves magnetised Finally, infer upper limit strength associated lower timescale action order redistribute angular momentum interiors.