Grantecan spectroscopic observations and confirmations of planetary nebulae candidates in the Northern Galactic Plane

Abstract

ABSTRACT We present Gran Telescopio Canarias (GTC) spectroscopic confirmations of 55 faint Planetary Nebulae (PNe) candidates discovered largely in the INT Photometric H α Survey (IPHAS) of the Northern Galactic Plane by our pro-am collaboration. We confirm 46 of them as ‘True’ (T), 4 as ‘Likely’ (L), and 5 as ‘Possible’ (P) PNe and including 5 new PNe central star (CSPN) discoveries. This was from observations of 62 new candidates yielding a maximum PN discovery success rate of 89 per cent. The sensitivity and longer wavelength coverage of IPHAS allows PNe to be found in regions of greater extinction and at these lower Galactic latitudes, including PNe in a more advanced evolutionary state and at larger distances compared to previously known Galactic PNe. We use a holistic set of observed characteristics and optical emission-line diagnostics to confirm candidates. Plasma properties have been determined in a self-consistent way using pyneb. This work is facilitated by the functionality of our powerful, multiwavelength database ‘HASH’ (Hong Kong, Australian Astronomical Observatory, Strasbourg Observatory H-alpha Planetary Nebula catalogue) that federates known imaging, spectroscopy, and other pertinent data for all Galactic T, L, P PNe, and the significant numbers of mimics. Reddenings, corrected radial velocities, and PNe electron density and temperature estimates are provided for these new PNe wherever possible.