SATELLITE: Application to Planetary Nebulae IFU Data

Stavros Akras,Hektor Monteiro,Isabel Aleman,Jeremy R Walsh,Panayotis Boumis,Denise R Gonçalves

doi:10.3390/galaxies10010027

Abstract

The integral field unit (IFU) spectroscopic view of extended ionized nebulae, such as planetary nebulae (PNe), H II regions, and galaxies, has changed the approach of studying these objects, providing a simultaneous characterization in both spatial directions. However, the spatial spaxel-by-spaxel analysis of such nebulae through IFUs is not directly comparable with the results obtained from the traditional slit-aperture spectroscopy or the predictions from 1D modelling. The new Python software called “satellite: Spectroscopic Analysis Tool for intEgraL fieLd unIt daTacubEs” is used in the analysis of the VIMOS and MUSE datacubes of four Galactic PNe. The 2D analysis of line ratio maps has shown important variations from one to another nebular component in NGC 7009 and NGC 6778. In particular, the knots in both PNe are characterized by strong emission from neutral gas that is weak or even absent from the main nebula, indicating significant variation in the ionization state and density structure among the nebular components. The far-UV radiation from the central star results in the photo-evaporation of the dense molecular knots resembling the spectrum of photodissociation regions.

Highlights

Planetary nebulae (PNe) are the descendants of low-to-intermediate mass stars (1–8 M )
The detection of only one of these two lines in each study above is likely related to the different slit positions (0 and 100 °C, respectively). 3D photo-ionization modelling of Abell 14 has shown that the intensity of the aforementioned auroral lines cannot be reproduced considering only the UV radiation field from its central stars (CS), and an additional thermal mechanism is needed [16]
Integral field spectroscopy has changed the way we study extended ionized nebulae, such as PNe galaxies or H II regions

Summary

Introduction

Planetary nebulae (PNe) are the descendants of low-to-intermediate mass stars (1–8 M ). PNe display a variety of shapes, such as round, elliptical, bipolar/multipolar, and point symmetric with different components, such as shells, rims, halos, knots, and filaments, among others This polymorphism of PNe is attributed to complex post-AGB mass-loss events and/or mass transfer between components in a binary system, the presence or not of a dense equatorial structure (disk or torus), formation of jets and clumps, etc. This structural complexity of PNe in conjunction with the UV radiation from the central stars results in an even more complex ionization and density stratification. Long-slit spectroscopic results are limited to specific directions or distinct components/features, such as low-ionization structures (LISs: knots, jets, and filaments; e.g., [1,2,3]) or bipolar outflows (e.g., [4,5,6]) due to the slit positioning

Methods

Results

Conclusion