H${}_2$ molecular gas in the old planetary nebula NGC 3587

Abstract

The acquisition of high-quality deep images of planetary nebulae (PNe) has allowed the detection of a wealth of small-scale features, which highlight the complexity of the formation history and physical processes shaping PNe. Here we present the discovery of three groups of clumps embedded within the nebular shell of the evolved PN NGC3587, the Owl Nebula, that had escaped previous detections. The analysis of multi-wavelength GEMINI GMOS, NOT ALFOSC, Aristarchos Andor optical, CFHT WIRCam and Spitzer IRAC and MIPS infrared (IR) images indicates that these clumps are formed by material denser and colder than the surrounding nebula, with a notable content of molecular H2, but negligible or null amounts of dust. The presence of H2-rich pockets embedded within the ionized shell of this evolved PN is suggestive of the survival of high-density condensations of material created at the onset of the PN stage.

8 pages, 6 figures, 1 tables. Accepted for publication in MNRAS

References in corpus (11)

• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Spectral Mapping Reconstruction of Extended Sources
• H${}_2$ in low-ionization structures of planetary nebulae
• Determination of the Physical Conditions of the Knots in the Helix Nebula from Optical and Infrared Observations
• VLT / Infrared Integral Field Spectrometer Observations of Molecular Hydrogen Lines in the Knots in the Planetary Nebula NGC 7293 (the Helix Nebula)
• The Herschel Planetary Nebula Survey (HerPlaNS) - a comprehensive dusty photoionization model of NGC6781
• Merged ionization/dissociation fronts in planetary nebulae
• H${}_2$ emission in the low-ionisation structures of the Planetary Nebulae NGC 7009 and NGC 6543
• Optical line profiles of the Helix planetary nebula (NGC 7293) to large radii
• Pushing the limits: detecting H2 emission from faint bipolar planetary nebulae in the IPHAS sample
• Low-ionization structures in planetary nebulae -- II. Densities, temperatures, abundances and excitation of 6 PNe