Flares of accretion activity of the 20 Myr old UXOR RZ Psc

TL;DR

This paper revises the understanding of accretion activity in the 20-million-year-old star RZ Psc, revealing episodic magnetospheric accretion and outflow signatures, and suggests its possible membership in the Cas-Tau OB association.

Contribution

It provides the first evidence of short-lived magnetospheric accretion episodes in RZ Psc, combining spectroscopic and astrometric data to refine its accretion behavior and galactic membership.

Findings

Detected episodic magnetospheric accretion via inverse P Cyg profiles.

Observed simultaneous accretion and outflow signatures in spectral lines.

Suggested RZ Psc's membership in the Cas-Tau OB association.

Abstract

We discuss a revision of accretion activity and kinematics of the enigmatic isolated UX Ori type star RZ Psc. Previously, RZ Psc was known to possess only spectroscopic signatures of outflow in the low-excitation lines of alkali metals. The archival high-resolution spectra reveal a short-lived episode of magnetospheric accretion in the system observed via inverse P Cyg profiles at the H$\alpha$ and CaII 8542 $\unicode{x212B}$ lines. The simultaneous presence of accretion and outflow signatures at CaII 8542 $\unicode{x212B}$ is suggestive of an accretion-driven origin of the RZ Psc wind. We argue that RZ Psc experiences matter ejection via the magnetic propeller mechanism but variable accretion episodes allow it to sometimes move in the magnetospheric accretion regime. The presence of the weak accretion in the system is also supported by the radiation of the hot accretion spot on the stellar surface observed spectroscopically at the deep photometric minimum of the star. The Galactic motion of RZ Psc calculated with new GAIA DR2 astrometric data suggests possible membership in Cas-Tau OB association with an age of $t=20^{+3}_{-5}$ Myr.