Establish the clumping distribution in the wind of AF And

Establish the exact radial distribution of inhomogeneities, including the location of the minimum filling factor, in the wind of AF And using additional observational constraints such as infrared data.

Background

The dynamically consistent wind models depend sensitively on the adopted filling-factor distribution. Previous studies provide conflicting expectations: some place the minimum filling factor near approximately 2 stellar radii, whereas radiation-hydrodynamic calculations place it farther out, at roughly 10–20 stellar radii.

For AF And, models with the filling-factor minimum near 10 stellar radii and models with an exponential clumping law reproduce the observed spectrum more successfully than models with the minimum near 2 stellar radii. However, the available observations do not uniquely determine the radial clumping structure, and the authors identify infrared observations as necessary to constrain it.

References

Due to the absence of IR data we are unable to reliably establish the exact form of $f(r)$ distribution, therefore we conclude that the minimum of inhomogeneities distribution is unlikely to be located in the close vicinity of the hydrostatic radius $R_*$.

— The study of AF And. I. Hydrogen abundance constraints and dynamically-consistent wind model of the hot state  (2609.16794 - Dedov et al., 15 Sep 2026) in Section 3.2, “Wind inhomogeneities”