| Abstract: | Planetary nebula have strikingly beautiful shapes including axial symmetries, clumps, ears, and lobes. These features point to binary interactions as the engines behind their formation. In particular, these features suggest a history involving common envelope evolution (CEE), where a giant star engulfs a companion, leading to an in-spiral that ejects the envelope and leaves behind the glowing remnant we observe. We explore a model in which the companion—a low-mass main sequence star—launches jets as it spirals inward. These jets inject energy into the envelope, inflating it and reducing the local density. This, in turn, lowers the accretion rate onto the companion and diminishes the jets' power, creating a negative feedback loop. Using the stellar evolution code MESA, we simulate this negative jet feedback mechanism during the early stages of CEE involving asymptotic giant branch (AGB) or red giant branch (RGB) stars. Our study is another step in establishing the major role of jets in the onset and early phase of common envelope evolution, a possible grazing envelope evolution phase, and in transient events, such as luminous red novae, which these processes can power. |