Is the Young Star RZ Piscium Consuming Its Own (Planetary) Offspring?

TL;DR

This study confirms RZ Piscium is a young, pre-main sequence star with circumstellar material, likely resulting from recent destruction of orbiting bodies, explaining its variability and infrared excess.

Contribution

The paper provides multi-wavelength observations confirming RZ Psc's young age and circumstellar environment, suggesting recent planetary body destruction.

Findings

RZ Psc is a young (~30-50 Myr) pre-main sequence star.

Evidence of circumstellar gas and debris from recent planetary destruction.

RZ Psc's space velocity aligns with young stellar groups near the Sun.

Abstract

The erratically variable star RZ Piscium (RZ Psc) displays extreme optical dropout events and strikingly large excess infrared emission. To ascertain the evolutionary status of this intriguing star, we obtained observations of RZ Psc with the European Space Agency's X-ray Multi-Mirror Mission (XMM-Newton), as well as high-resolution optical spectroscopy with the Hamilton Echelle on the Lick Shane 3 m telescope and with HIRES on the Keck I 10 m telescope. The optical spectroscopy data demonstrate that RZ Psc is a pre-main sequence star with an effective temperature of 5600 $\pm$ 75 K and log g of 4.35 $\pm$ 0.10. The ratio of X-ray to bolometric luminosity, log L$_{X}$/L$_{bol}$, lies in the range -3.7 to -3.2, consistent with ratios typical of young, solar-mass stars, thereby providing strong support for the young star status of RZ Psc. The Li absorption line strength of RZ Psc suggests an age in the range 30-50 Myr, which in turn implies that RZ Psc lies at a distance of $\sim$170 pc. Adopting this estimated distance, we find the Galactic space velocity of RZ Psc to be similar to the space velocities of stars in young moving groups near the Sun. Optical spectral features indicative of activity and/or circumstellar material are present in our spectra over multiple epochs, which provide evidence for the presence of a significant mass of circumstellar gas associated with RZ Psc. We suggest that the destruction of one or more massive orbiting bodies has recently occurred within 1 au of the star, and we are viewing the aftermath of such an event along the plane of the orbiting debris.