New Young Planetary Nebulae in IPHAS

TL;DR

This study identifies and confirms 83 candidate young planetary nebulae in the IPHAS survey, including five likely new PNe, and estimates their distances, contributing to understanding early PN evolution.

Contribution

The paper introduces a new method for selecting small-diameter PN candidates using IPHAS and 2MASS data, with spectroscopic confirmation and distance estimates for the first time.

Findings

83 PN candidates identified, 35 classified

5 likely new PNe discovered, including a bipolar PN

Distances estimated between 2 and 6 kpc

Abstract

We search for very small-diameter galactic planetary nebulae (PNe) representing the earliest phases of PN evolution. A recently published IPHAS catalogue of Ha-emitting stars provides a useful base for this study as all sources present in this catalogue must be of small angular diameter. The PN candidates are selected based on their location in two colour-colour diagrams: IPHAS (r' - Ha) vs. (r' - i'), and 2MASS (J - H) vs. (H - Ks). Spectroscopic follow-up has been carried out on a sample of candidates in order to confirm their nature. We present a total of 83 PN candidates. We were able to obtain spectra or find the classification from the literature for 35 candidates. Five of these objects are likely to be new PNe, including one large bipolar PN discovered serendipitously near an emission-line star. PN distances deduced from extinction-distance relations based on IPHAS field-star photometry are presented for the first time. These yield distance estimates for our objects in the range from 2 kpc to 6 kpc. From the data to hand, we conclude that four of the discovered objects are very probably young PNe.