A summary of two meetings on the role of jets in interacting stellar binaries

Abstract

In relation to two meetings on stellar binary systems in July 2017, I summarize my view that in the majority of strongly interacting stellar binary systems jets play decisive roles. In the meeting The Physics of Evolved Stars II: The role of Binarity (Nice, July 10-13, 2017) many talks and posters were concentrated on the shaping of circumstellar matter, with some significant new results, like the observations of wide jets launched from binary systems. In the meeting The Impact of Binaries on Stellar Evolution (ESO Garching, July 3-7, 2017), both in the opening and the summary talks the speakers mentioned that "Textbooks need most likely to be rewritten". I made my point that some new chapters were already written, although researchers do not read them but rather keep referring to the `old textbooks'. For example, too many speakers and authors keep referring only to the single degenerate and double degenerate scenarios for the progenitors of SNe Ia. Researchers must refer also to the `new textbook chapter' on the core degenerate (CD) scenario. Other examples involve the role of jets. Jets lead to a new evolutionary phase, that of the grazing envelope evolution (GEE), that should be considered alongside the older ones, e.g., the common envelope evolution, Roche lobe overflow (RLOF), and wind mass loss and accretion. I discuss how the GEE can solve some puzzling binary systems. We should also consider the role of jets as an extra energy source to remove the common envelope and in powering intermediate luminosity optical transients (ILOTs). One strong advantage of jets is that in many cases they operate through a negative feedback mechanism, hence preventing the need for a fine tuning. The operation of the jet feedback mechanism (JFM) connects also binary evolution to explosion of massive stars as core collapse supernovae.