Physical versus numerical origin of post-accretion structural features

Ascertain whether the small-scale features and glitches observed in the Brunt–Väisälä frequency and composition-gradient profiles of mass-accreting main-sequence stars in one-dimensional MESA models after mass transfer are physical signatures of mass-transfer-driven rejuvenation or numerical artifacts arising from one-dimensional discretization and the imposed minimum diffusive mixing coefficient.

Background

In their discussion of steep chemical gradients produced by mass transfer and rejuvenation, the authors note that the one-dimensional modeling approach in MESA requires imposing a minimum diffusive mixing coefficient to smooth unphysically sharp gradients. Lower values of this parameter can introduce mesh-point scale spikes (“glitches”) in the Brunt–Väisälä frequency profile.

Because mass transfer is rapid and poorly understood, the authors caution that it is unclear whether certain observed features—especially the glitches highlighted in their Brunt–Väisälä profiles—are genuine physical imprints of accretion-induced structural changes or artifacts of the numerical treatment and discretization. Resolving this ambiguity is essential for robustly interpreting asteroseismic diagnostics of mass transfer.