Characterisation of the Planetary Nebula Tc 1 Based on VLT X-Shooter Observations

TL;DR

This paper provides a comprehensive analysis of the planetary nebula Tc 1 using VLT/X-Shooter data, revealing its 3D structure, physical conditions, and chemical abundances, including the first detection of Krypton emission.

Contribution

It introduces a detailed 3D morphological model of Tc 1 and reports the first detection of Krypton emission in this nebula, advancing understanding of its structure and composition.

Findings

Tc 1 is a slightly elongated spheroid with equatorial density enhancement.

Detected Krypton emission line allows for Krypton abundance measurement.

Photoionization models match observed properties and suggest the nebula is matter bounded.

Abstract

We present a detailed analysis of deep VLT/X-Shooter observations of the planetary nebula Tc 1. We calculate gas temperature, density, extinction, and abundances for several species from the empirical analysis of the total line fluxes. In addition, a spatially resolved analysis of the most intense lines provides the distribution of such quantities across the nebula. The new data reveal that several lines exhibit a double peak spectral profile consistent with the blue- and red-shifted components of an expanding spherical shell. The study of such components allowed us to construct for the first time a three-dimensional morphological model, which reveals that Tc 1 is a slightly elongated spheroid with an equatorial density enhancement seen almost pole on. A few bright lines present extended wings (with velocities up to a few hundred km/s), but the mechanism producing them is not clear. We constructed photoionization models for the main shell of Tc 1. The models predict the central star temperature and luminosity, as well as the nebular density and abundances similar to previous studies. Our models indicate that Tc 1 is located at a distance of approximately 2 kpc. We report the first detection of the [Kr III] 6825 A emission line, from which we determine the Krypton abundance. Our model indicates that the main shell of Tc 1 is matter bounded; leaking H ionizing photons may explain the ionization of its faint AGB-remnant halo.