Project description
Shedding new light on binary star evolution
Common envelope evolution (CEE) refers to a short yet important phase in the evolution of a binary system where two stars strongly interact and either lose large amounts of mass or merge into a single object. CEE is expected to be accompanied by a rise in luminosity represented as a red transient event. However, several red transient features challenge the existing CEE paradigm. The EU-funded Cat-In-hAT project will use a new variant of magnetohydrodynamics to examine the 3D dynamics of CEE from the moment the mass loss commences to the remnant phase. By considering the implications for a wide range of astrophysical objects, the project will provide further insight into this important phenomenon.
Objective
"One of the crucial formation channels of compact object binaries, including sources of gravitational waves, critically depends on catastrophic binary interactions accompanied by the loss of mass, angular momentum, and energy (""common envelope"" evolution - CEE). Despite its importance, CEE is perhaps the least understood major phase of binary star evolution and progress in this area is urgently needed to interpret observations from the new facilities (gravitational wave detectors, time-domain surveys).
Recently, the dynamical phase of the CEE has been associated with a class of transient brightenings exhibiting slow expansion velocities and copious formation of dust and molecules (red transients - RT). A number of RT features, especially the long timescale of mass loss, challenge the existing CEE paradigm.
Motivated by RT, I will use a new variant of magnetohydrodynamics to comprehensively examine the 3D evolution of CEE from the moment when the mass loss commences to the remnant phase. I expect to resolve the long timescales observed in RT, characterize binary stability in 3D with detailed microphysics, illuminate the fundamental problem of how is orbital energy used to unbind the common envelope in a regime that was inaccessible before, and break new ground on the amplification of magnetic fields during CEE.
I will establish RT as an entirely new probe of the CEE physics by comparing my detailed theoretical predictions of light curves from different viewing angles, spectra, line profiles, and polarimetric signatures with observations of RT. I will accomplish this by coupling multi-dimensional moving mesh hydrodynamics with radiation, dust formation, and chemical reactions. Finally, I will examine the physical processes in RT remnants on timescales of years to centuries after the outburst to connect RT with the proposed merger products and to identify them in time-domain surveys.
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Funding Scheme
ERC-STG - Starting GrantHost institution
116 36 Praha 1
Czechia