The evolutionary status of the UX Orionis star RZ Piscium

TL;DR

This paper investigates the evolutionary status of RZ Psc, a star exhibiting UX Ori-like variability but lacking youth signatures, concluding it is a post-UXOr star with a debris disk, aged around 30-70 million years.

Contribution

It provides the first detailed age estimate of RZ Psc using lithium lines and proper motion, suggesting it is a post-UXOr star rather than a young stellar object.

Findings

RZ Psc's lithium age is between 10 and 70 million years.

Proper motion analysis indicates it left its birthplace 30-40 million years ago.

RZ Psc's variability is caused by debris disk material, not youth-related phenomena.

Abstract

The star RZ Psc is one of the most enigmatic members of the UX Ori star family. It shows all properties that are typical for these stars (the light variability, high linear polarization in deep minima, the blueing effect) except for one: it lacks any signatures of youth. With the Li I line, as a rough estimate for the stellar age, we show that the "lithium" age of RZ Psc lies between the age of stars in the Pleiades (approximately 70 Myr) and the Orion (approximately 10 Myr) clusters. We also roughly estimated the age of RZ Psc based on the proper motion of the star using the Tycho-2 catalog. We found that the star has escaped from its assumed birthplace near to the Galactic plane about 30-40 Myr ago. We conclude that RZ Psc is a post-UXOr star, and its sporadic eclipses are caused by material from the debris disk.