Candidate planetary nebulae in the IPHAS photometric catalogue

TL;DR

This study conducts a semi-automated search for planetary nebulae in the IPHAS survey, identifying 781 new candidates and providing a methodology for their selection and preliminary classification.

Contribution

The paper introduces a novel semi-automated approach to identify PN candidates in the IPHAS survey, including criteria to refine candidate selection and estimate the number of true PNe.

Findings

Identified 781 new PN candidates from 600 million IPHAS detections.

Spectroscopic follow-up suggests ~16% are genuine PNe or related objects.

Provided criteria to improve candidate selection accuracy.

Abstract

Context. We have carried out a semi-automated search for planetary nebulae (PNe) in the INT Photometric H-Alpha Survey (IPHAS) catalogue. We present the PN search and the list of selected candidates. We cross correlate the selected candidates with a number of existing infrared galactic surveys in order to gain further insight into the nature of the candidates. Spectroscopy of a subset of objects is used to estimate the number of PNe present in the entire candidate list. Aims. The overall aim of the IPHAS PN project is to carry out a deep census of PNe in the northern Galactic plane, an area where PN detections are clearly lacking. Methods. The PN search is carried out on the IPHAS photometric catalogues. The candidate selection is based on the IPHAS and 2MASS/UKIDSS colours of the objects and the final candidate selection is made visually. Results. From the original list of ~600 million IPHAS detections we have selected a total of 1005 objects. Of these, 224 are known objects, leaving us with 781 PN candidates. Based on the initial follow-up spectroscopy, we expect the list to include very young and proto-PNe in addition to genuine, normal PNe (~16 %) and emission line objects other than PNe. We present additional criteria to select the most probable PN candidates from our candidate list.