Binary stellar interactions is arguably one of the most actively developing fields of astrophysics. Thousands of papers are published on the topic every year, and, with increasing success, the theory underpins most of the diverse stellar exotica we observe today.

Binary stellar interactions come in two main categories: systems interacting on long timescales through stable mass transfer and systems undergoing dynamical common envelope evolution or mergers. The specific path a given binary chooses depends on our understanding of stellar interactions, such as tidal interactions, mass and angular momentum loss. Stars currently undergoing interactions are observed as cataclysmic variables, X-ray binaries, symbiotic binaries, AM CVn systems, among others. Stars that experienced a merger or dynamical common envelope ejection produce a variety of multimessenger sources, including binary neutron stars and black holes, as well as double white dwarf binaries, magnetic massive stars, and (blue) stragglers, among others. Because of this diversity, interacting binaries have been traditionally observed with very different techniques, including UV, optical, NIR, X-rays, radio, and GWs, and they have been traditionally studied by different communities. Ensuring that consistent binary interaction models are used by these diverse communities is critically important for the field to progress.

However, several more important probes of binary interactions exist. These include the transients that occur during the interactions, such as luminous red novae, the transients that have been affected by interactions, such as stripped supernovae, or the nebulous remnants that may indicate the recent phase of interaction.

At this stage, gathering a unified vision of binary interactions from these disjoint research areas is critically important, both observationally and theoretically. The EAS Symposium format is perfectly and uniquely suited for this purpose because a large number of researchers with diverse expertise will be attending the meeting. In the program, we wish to gather talks about representative objects from different fields, foster a common vision, initiate a unique novel discussion, and motivate the community to collaborate on these newly developed ideas. This way, the success of this Symposium will increase the predictive power of the current binary interaction models.

Programme

The Symposium will consist of the following six topics:

1. Mass transferring and close binaries (e.g. manifestations of mass transfer, stability, accretion efficiency, angular momentum loss, stellar evolution modified by interactions)
2. Common envelope evolution and stellar mergers (e.g. onset, dynamical phase, post-interaction phase, dependence on the stellar components)
3. Binary-powered transients (e.g. MS/MS, MS/WD mergers, luminous red novae, planetary engulfment)
4. Binary nature of interacting supernovae (e.g. circumstellar matter, pre-supernova eruptions, jets, signatures of binary interactions)
5. Nebulae (e.g. planetary nebulae, wind-blown nebulae, supernova remnants, water fountains)
6. Combinations of surveys and population synthesis (e.g. synthesised populations, population-based constraints on binary interactions, well-understood populations, unexplained populations)

Invited speakers

• Jakub Klencki (Max Planck Institute for Astronomy, Garching)
• Mike Lau (Heidelberg Institute for Theoretical Studies)
• Tomasz Kamiński (Nicolaus Copernicus Astronomical Center in Toruń)
• Morgan Fraser (University College Dublin)
• Javier Alcolea (Observatorio Astronómico Nacional, Madrid)
• Simon Jeffery (Armagh Observatory and Planetarium)

Scientific organisers

• Alexey Bobrick (chair, Monash University)
• Hila Glanz (chair, Technion Institute)
• Friedrich Roepke (Heidelberg Institute for Theoretical Studies)
• Silvia Toonen (University of Amsterdam)
• Nadezhda Blagorodnova (University of Barcelona)

Contact

• Alexey Bobrick (alexey.bobrick @ monash.edu)
• Hila Glanz (glanz @ campus.technion.ac.il)