Convection, Radiation, and the Instantaneous Mass Transfer in Red Supergiant Binaries: A 3D Simulation Analysis

Abstract: Understanding mass transfer in Red Supergiant (RSG) binary systems is challenged by the dynamic, three-dimensional nature of stellar convection and radiation, which are often simplified or time-averaged in traditional models. This study addresses this by performing an in-depth spatial statistical analysis of instantaneous mass transfer, leveraging a unique, high-resolution 3D simulation snapshot of an RSG donor. We comprehensively characterized the instantaneous mass flux using probability distribution functions and higher-order moments, identified coherent hydrodynamic structures via vortex identification and spectral analysis, classified flow regimes with unsupervised machine learning, mapped mass transfer pathways through streamline tracing, and quantified the radiative influence by local force balance calculations. Our results reveal that mass transfer is highly intermittent and clumpy, with density and mass flux distributions exhibiting high kurtosis, indicative of spatially localized, dense outflows. Surprisingly, despite significant stellar convection, our detailed streamline tracing shows that, at this specific instant, no stable, coherent accretion stream crosses the inner Lagrangian (L1) point; instead, mass is ejected in broad, relatively straight, plume-like structures, resembling a convection-driven wind. Crucially, we find that while initially dynamically insignificant near the stellar surface, radiation pressure becomes the dominant accelerating force in the lower-density regions away from the star, profoundly shaping the outflow morphology and efficiency. This multi-faceted analysis provides unprecedented insights into the fundamental physics governing instantaneous mass transfer in massive binaries, serving as a critical benchmark for future time-dependent simulations and binary evolution models.

Subjects:	astro-ph.CO; cs.LG
Cite as:	PX:2508.00015