Unveiling the Inhomogeneous 3D Mass Transfer Stream in a Red Supergiant Binary: From Convective Driving to Clumpy Outflows

Abstract: Mass transfer in binary systems is a fundamental process dictating their evolution, yet a detailed, instantaneous three-dimensional understanding of how stellar convection and the local radiation field shape the mass transfer stream remains elusive. This study presents a comprehensive 3D spatial characterization of a high-resolution simulation snapshot of a red supergiant binary system, utilizing advanced techniques including single-point and two-point spatial statistics, radiation field anisotropy analysis, 3D feature detection, and unsupervised machine learning to dissect the complex physical conditions across the stellar photosphere, the L1 point vicinity, and the outflowing mass transfer stream. Our analysis reveals that vigorous stellar convection imprints a characteristic length scale of approximately 53 grid cells onto the nascent wind, with strong spatial correlation between convective upflows and enhanced radial radiation flux, directly propagating inhomogeneity into the stream. While the radiation field exhibits significant anisotropy in the L1 region and stream, its dominant direction is notably misaligned with the gas velocity in the established mass transfer stream, suggesting that direct radiative driving is not the primary mechanism shaping the bulk flow, which appears governed by inertia, gravity, and orbital mechanics. Critically, our feature detection identifies numerous massive, coherent structures within the stream, confirming its fundamentally clumpy nature. Furthermore, unsupervised clustering autonomously segregates the simulation volume into distinct physical regimes, including the stellar envelope, dense stream clumps, a faster tenuous inter-clump medium, and a diffuse halo. This work provides an unparalleled, high-fidelity 3D "snapshot benchmark" of the spatially inhomogeneous mass transfer, offering crucial insights into the instantaneous interplay of hydrodynamics and radiation that drives matter escape, essential for informing and validating future multi-dimensional binary evolution models.

Subjects:	astro-ph.CO; cs.LG
Cite as:	PX:2508.00014