The Coordinated Radio and Infrared Survey for High-mass Star Formation. IV: A new radio selected sample of compact Galactic Planetary Nebulae

TL;DR

This paper introduces a new radio-selected sample of planetary nebulae in the Galactic plane, utilizing multi-wavelength data to verify and classify candidates, including newly discovered and confirmed PNe, aiding in understanding their formation and evolution.

Contribution

The study presents the first large, unbiased radio-selected sample of Galactic PNe, with detailed multi-wavelength analysis leading to new discoveries and classifications, improving completeness and understanding of PNe populations.

Findings

Identified 90 new PNe, including 12 newly discovered.

Confirmed 47 suspected PNe and detected 24 known PNe.

Discovered a water-maser PN with non-thermal radio emission.

Abstract

We present a new radio-selected sample of PNe from the CORNISH survey. This is a radio continuum survey of the inner Galactic plane covering Galactic longitude, $10^\circ <l< 65^\circ$ and latitude, $|b| < 1^\circ$ with a resolution of 1.5$^{"}$ and sensitivity better than 0.4 mJy/beam. The radio regime, being unbiased by dust extinction, allows for a more complete sample selection, especially towards the Galactic mid-plane. Visual inspection of the CORNISH data, in combination with data from multi-wavelength surveys of the Galactic plane, allowed the CORNISH team to identify 169 candidate PNe. Here, we explore the use of multi-wavelength diagnostic plots and analysis to verify and classify the candidate PNe. We present the multi-wavelength properties of this new PNe sample. We find 90 new PNe, of which 12 are newly discovered and 78 are newly classified as PN. A further 47 previously suspected PNe are confirmed as such from the analysis presented here and 24 known PNe are detected. Eight sources are classified as possible PNe or other source types. Our sample includes a young sub-sample, with physical diameters < 0.12 pc, brightness temperatures (> 1000 K) and located closer than 7 kpc. Within this sample is a water-maser PN with a spectral index of $-0.55\pm 0.08$, which indicates non-thermal radio emission. Such a radio-selected sample, unaffected by extinction, will be particularly useful to compare with population synthesis models and should contribute to the understanding of the formation and evolution of PNe.