Chandra X-ray Detection of the Enigmatic Field Star BP Psc

TL;DR

This study reports the first X-ray detection of BP Psc, a star with a dusty disk and jets, suggesting magnetic activity possibly due to recent engulfment of a companion, with implications for its evolutionary status.

Contribution

First X-ray detection of BP Psc, providing insights into its magnetic activity and supporting a model of recent stellar engulfment.

Findings

X-ray emission likely from magnetic activity at BP Psc

X-ray to bolometric luminosity ratio consistent with giant stars

Supports the star's recent engulfment of a companion or planet

Abstract

BP Psc is a remarkable emission-line field star that is orbited by a dusty disk and drives a parsec-scale system of jets. We report the detection by the Chandra X-ray Observatory of a weak X-ray point source coincident with the centroids of optical/IR and submillimeter continuum emission at BP Psc. As the star's photosphere is obscured throughout the visible and near-infrared, the Chandra X-ray source likely represents the first detection of BP Psc itself. The X-rays most likely originate with magnetic activity at BP Psc and hence can be attributed either to a stellar corona or to star-disk interactions. The log of the ratio of X-ray to bolometric luminosity (log(L_X/L_{bol}) lies in the range -5.8 to -4.2. This is smaller than log(L_X/L_{bol}) ratios typical of low-mass, pre-main sequence stars, but is well within the log(L_X/L_{bol}) range observed for rapidly-rotating (FK Com-type) G giant stars. Hence, the Chandra results favor an exotic model wherein the disk/jet system of BP Psc is the result of its very recently engulfing a companion star or giant planet, as the primary star ascended the giant branch.