The physical structure of planetary nebulae around sdO stars: Abell36, DeHt2, and RWT152

TL;DR

This study investigates the morphology and internal kinematics of three planetary nebulae around sdO stars, revealing complex structures, multiple ejection events, and high excitation spectra, contributing to understanding their evolution.

Contribution

It provides detailed morphokinematical analysis of three PNe around sdO stars, highlighting their complex structures and evolutionary implications, which is novel in the context of sdO-PNe systems.

Findings

Abell36 has an inner spheroid with point-symmetric arcs

DeHt2 is elliptical with polar protrusions and a ring

RWT152 exhibits bipolar morphology

Abstract

We present narrow-band Halpha and [OIII] images, and high-resolution, long-slit spectra of the planetary nebulae (PNe) Abell36, DeHt2, and RWT152 aimed at studying their morphology and internal kinematics. These data are complemented with intermediate-resolution, long-slit spectra to describe the spectral properties of the central stars and nebulae. The morphokinematical analysis shows that Abell36 consists of an inner spheroid and two bright point-symmetric arcs; DeHt2 is elliptical with protruding polar regions and a bright non-equatorial ring; and RWT152 is bipolar. The formation of Abell36 and DeHt2 requires several ejection events including collimated bipolar outflows that probably are younger than and have disrupted the main shell. The nebular spectra of the three PNe show a high excitation and also suggest a possible deficiency in heavy elements in DeHt2 and RWT152. The spectra of the central stars strongly suggest an sdO nature and their association with PNe points out that they have most probably evolved through the asymptotic giant branch. We analyze general properties of the few known sdOs associated to PNe and find that most of them are relatively or very evolved PNe, show complex morphologies, host binary central stars, and are located at relatively high Galactic latitudes.