Discovery and characterisation of a new Galactic Planetary Nebula

Abstract

Planetary nebulae are one of the final stages in the evolution of low and intermediate mass stars. They occur in a variety of shapes. Older and fainter ones are generally more difficult to identify because of the lower surface brightness. This paper reports the serendipitous discovery of a new faint Galactic planetary nebula (PN), during a campaign to identify dwarf galaxies, companions of the spiral galaxy NGC 2403. We aim at confirming the nature as PN of a diffuse object identified in the Camelopardalis constellation. We obtained narrow-band filter images and spectra of the nebula and its central star with amateur and professional telescopes having diameters from 20 cm to 6 m. We detected a dense triangular nebula, surrounded by an elliptical region, named Cam nebula. They are part of a larger and fainter circular nebular structure, named TBG-1, at the centre of which we have identified the possible central star, a white dwarf with a temperature of about 22 000 K. The analysis of the spectrum made it possible to measure the physical characteristics of the nebula, in particular its electronic density and temperature. Analysis of the images, of the spectra of the nebula and of the central star confirm the PN nature of TBG-1, located at the distance of about 1 kpc. This work reaffirms the potential for fruitful collaborations between astronomers and amateur astronomers in the detection and study of new objects.