# The transiting dust clumps in the evolved disk of the Sun-like UXor RZ Psc

## TL;DR

This study analyzes a decade of optical data of RZ Psc, a Sun-like star with dust clumps causing dimming, to understand the nature of its circumstellar disk and the origin of its variability.

## Contribution

It provides a critical assessment of the asteroid belt hypothesis and explores the disk structure, offering new insights into the star's circumstellar environment.

## Key findings

- Deep event gradients suggest clump structures similar to asteroidal fragments.
- High optical depth likely obscures the disk's bulk clumpiness.
- Circumstantial evidence favors an asteroid belt over a gas-rich disk.

## Abstract

RZ Psc is a young Sun-like star, long associated with the UXor class of variable stars, which is partially or wholly dimmed by dust clumps several times each year. The system has a bright and variable infrared excess, which has been interpreted as evidence that the dimming events are the passage of asteroidal fragments in front of the host star. Here, we present a decade of optical photometry of RZ Psc and take a critical look at the asteroid belt interpretation. We show that the distribution of light curve gradients is non-uniform for deep events, which we interpret as possible evidence for an asteroidal fragment-like clump structure. However, the clumps are very likely seen above a high optical depth mid-plane, so the disk's bulk clumpiness is not revealed. While circumstantial evidence suggests an asteroid belt is more plausible than a gas-rich transition disk, the evolutionary status remains uncertain. We suggest that the rarity of Sun-like stars showing disk-related variability may arise because i) any accretion streams are transparent, and/or ii) turbulence above the inner rim is normally shadowed by a flared outer disk.