BP Piscium: its flaring disk imaged with SPHERE/ZIMPOL

TL;DR

This study uses high-resolution polarimetric imaging and radiative transfer modeling to analyze BP Piscium's disk, revealing a strongly flared structure atypical for T Tauri stars, which informs its evolutionary status.

Contribution

It provides the first visible light polarization images of BP Psc's disk and compares observations with models to determine its geometry and nature.

Findings

Disk shows a high inclination flared shape.

Radiative transfer modeling indicates a strongly flared disk.

Disk features suggest an atypical structure for T Tauri stars.

Abstract

Whether BP Piscium (BP Psc) is either a pre-main sequence T Tauri star at d ~ 80 pc, or a post-main sequence G giant at d ~ 300 pc is still not clear. As a first-ascent giant, it is the first to be observed with a molecular and dust disk. Alternatively, BP Psc would be among the nearest T Tauri stars with a protoplanetary disk (PPD). We investigate whether the disk geometry resembles typical PPDs, by comparing polarimetric images with radiative transfer models. Our VLT/SPHERE/ZIMPOL observations allow us to perform Polarimetric Differential Imaging; Reference Star Differential Imaging; and Richardson-Lucy deconvolution. We present the first visible light polarization and intensity images of the disk of BP Psc. Our deconvolution confirms the disk shape as detected before, mainly showing the southern side of the disk. In polarized intensity the disk is imaged at larger detail and also shows the northern side, giving it the typical shape of high inclination flared disks. We explain the observed disk features by retrieving the large-scale geometry with MCMax radiative transfer modeling, which yields a strongly flared model, atypical for disks of T Tauri stars.