We discuss ASASSN-24fw, a 13th-magnitude star that optically faded by Δg=4.12±0.02 mag starting in September 2024 after over a decade of quiescence in ASAS-SN. The dimmimg lasted 8 months before returning to quiescence in late May 2025. The spectral energy distribution (SED) before the event is that of a pre-main sequence or a modestly evolved F star with some warm dust emission. The shape of the optical SED during the dim phase is unchanged and the optical and near-infrared spectra are those of an F star. The SED and the dilution of some of the F star infrared absorption features near minimum suggest the presence of a $ 0.25M_$ M dwarf binary companion. The 43.8 year period proposed by Nair & Denisenko (2024) appears correct and is probably half the precession period of a circumbinary disk. The optical eclipse is nearly achromatic, although slightly deeper in bluer filters, Δ(g−z)=0.31±0.15 mag, and the V band emission is polarized by up to 4%. The materials most able to produce such small optical color changes and a high polarization are big (20 μm) carbonaceous or water ice grains. Particle distributions dominated by big grains are seen in protoplanetary disks, Saturn-like ring systems and evolved debris disks. We also carry out a survey of occultation events, finding 46 additional systems, of which only 7 (4) closely match ε Aurigae (KH 15D), the two archetypes of stars with long and deep eclipses. The full sample is widely distributed in an optical color-magnitude diagram, but roughly half show a mid-IR excess. It is likely many of the others have cooler dust since it seems essential to produce the events.

https://ui.adsabs.harvard.edu/abs/2025OJAp....8E.114F/abstract