Description du projet
Un nouvel éclairage sur l’évolution des étoiles binaires
L’évolution de l’enveloppe commune (EEC) fait référence à une phase courte mais importante de l’évolution d’un système binaire où deux étoiles interagissent fortement et soit perdent de grandes quantités de masse, soit fusionnent en un seul corps. L’EEC devrait s’accompagner d’une augmentation de la luminosité représentée par un événement transitoire rouge. Cependant, plusieurs caractéristiques transitoires rouges remettent en question le paradigme actuel de l’EEC. Le projet Cat-In-hAT, financé par l’UE, recourra à une nouvelle variante de la magnétohydrodynamique pour examiner la dynamique 3D de l’EEC depuis le début de la perte de masse jusqu’à la phase résiduelle. En considérant les implications pour un large éventail d’objets astrophysiques, le projet permettra de mieux appréhender cet important phénomène.
Objectif
"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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ERC-STG - Starting GrantInstitution d’accueil
116 36 Praha 1
Tchéquie