VLT/X-shooter Spectroscopy of a Dusty Planetary Nebula Discovered with Spitzer/IRS

TL;DR

This paper reports the classification of a dusty planetary nebula discovered via Spitzer/IRS, using VLT/X-shooter spectroscopy to analyze emission lines and determine its nature among other possibilities.

Contribution

It demonstrates the effectiveness of X-shooter spectroscopy in identifying and classifying faint, complex astronomical objects like planetary nebulae.

Findings

The object is confirmed as a planetary nebula.

Spectroscopic data reveal strong, narrow emission lines.

The nebula is located behind the Serpens Molecular Cloud.

Abstract

As part of a mid-infrared spectroscopic survey of young stars with the Spitzer Space Telescope, an unclassified red emission line object was discovered. Based on its high ionization state indicated by the Spitzer spectrum, this object could either be a dusty Supernova Remnant (SNR) or a Planetary Nebula (PN). In this research note, the object is classified and the available spectroscopic data are presented to the community for further analysis. UV/optical/NIR spectra were obtained during the science verification run of the VLT/X-shooter. A large number of emission lines are identified allowing the determination of the nature of this object. The presence of strong, narrow (Delta_v ~ 8 - 74 km/s) emission lines, combined with very low line ratios of, e.g., [N II]/Halpha and [S II]/Halpha show that the object is a Planetary Nebula (PN) that lies at an undetermined distance behind the Serpens Molecular Cloud. This illustrates the potential of X-shooter as an efficient tool for constraining the nature of faint sources with unknown spectral properties or colors.