Raúl Maldonado, IRyA
Host: Jesus Toala
The Impact of Wind Accretion in Evolving Symbiotic Systems
Symbiotic binary systems, where a white dwarf (WD) accretes material from an evolved companion, exhibit diverse orbital configurations and accretion regimes. Understanding how wind accretion, drag forces, and tides influence their long-term evolution is essential to determine under which conditions a WD can substantially grow in mass, to ultimately explode as a supernova event. Using stellar evolution models from MESA coupled with REBOUND N-body simulations, we model binaries with WD masses of 0.7–1.2 Msun and donor stars of 1–3 Msun, evolving through the red giant and asymptotic giant branch phases. In wide systems (a ≥ 8 AU), accretion occurs purely through stellar winds. The classical Bondi–Hoyle–Lyttleton (BHL) formalism predicts a few cases reaching the Chandrasekhar limit due to an overestimation of the efficiency in the low wind-velocity regime, whereas a geometric correction accounting for the wind-to-orbital velocity ratio yields lower, more realistic accretion rates, reproducing the properties of observed symbiotic binaries. In compact systems (a ≤ 7 AU), drag and tidal forces drive orbital contraction, and most models evolve successively through wind accretion, Wind Roche Lobe Overflow (WRLO), and terminate in Roche lobe overflow. The resulting final separations agree with those of observed compact systems, suggesting that tides and wind interactions are key in shaping their orbital evolution. Systems that undergo WRLO episodes, particularly those with massive WDs and donors, may represent potential Type Ia supernova channels.