Searching for dark energy with the Sun

General extensions of general relativity (GR) based on bona fide degrees freedom predict a fifth force which operates within massive objects, opening up an exciting opportunity to perform precision tests gravity at stellar scales. Here, focussing scalar-tensor theories for dark energy, we utilise the Sun as our laboratory and search imprints fifth-force effect solar equilibrium structure. With analytic results numerical simulations, explain how different regions offer powerful ways test gravity. Accounting delicate interplay between microphysics such opacity, diffusion, equation state, metallicity, demonstrate that still leaves sharp signature sound speed, in region where simple estimates input physics uncertainties become negligible. For scalar-field GR, known (U-)DHOST, solely observational helioseismic errors, analysis level allows us place approximate constraint coupling strength −10 −3 ≲