Discovery of a [WO] central star in the planetary nebula Th 2-A

TL;DR

This paper reports the discovery and spectral classification of a [WO] type central star in the planetary nebula Th 2-A, expanding the known catalog of such stars and providing insights into its properties.

Contribution

First spectral identification of a [WO] central star in Th 2-A, demonstrating the effectiveness of spectroscopy in classifying planetary nebulae central stars.

Findings

Central star of Th 2-A classified as [WO 3]pec.

Spectra show ionized C and O emission lines.

Central star is not the brightest in the pair.

Abstract

% context About 2500 planetary nebulae are known in our Galaxy but only 224 have central stars with reported spectral types in the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (Acker et al. 1992; Acker et al. 1996) % aims We have started an observational program aiming to increase the number of PN central stars with spectral classification. % methods By means of spectroscopy and high resolution imaging, we identify the position and true nature of the central star. We carried out low resolution spectroscopic observations at CASLEO telescope, complemented with medium resolution spectroscopy performed at Gemini South and Magellan telescopes. % results As a first outcome of this survey, we present for the first time the spectra of the central star of the PN Th 2-A. These spectra show emission lines of ionized C and O, typical in Wolf-Rayet stars. % conclusions We identify the position of that central star, which is not the brightest one of the visual central pair. We classify it as of type [WO 3]pec, which is consistent with the high excitation and dynamical age of the nebula.