TheHerschelPlanetary Nebula Survey (HerPlaNS)

Abstract

Context. This is the first of a series of investigations into far-IR characteristics of 11 planetary nebulae (PNe) under the Herschel Space Observatory open time 1 program, Herschel Planetary Nebula Survey (HerPlaNS). Aims. Using the HerPlaNS data set, we look into the PN energetics and variations of the physical conditions within the target nebulae. In the present work, we provide an overview of the survey, data acquisition and processing, and resulting data products. Methods. We performed (1) PACS/SPIRE broadband imaging to determine the spatial distribution of the cold dust component in the target PNe and (2) PACS/SPIRE spectral-energy-distribution and line spectroscopy to determine the spatial distribution of the gas component in the target PNe. Results. For the case of NGC 6781, the broadband maps confirm the nearly pole-on barrel structure of the amorphous carbon-rich dust shell and the surrounding halo having temperatures of 26−40 K. The PACS/SPIRE multiposition spectra show spatial variations of far-IR lines that reflect the physical stratification of the nebula. We demonstrate that spatially resolved far-IR line diagnostics yield the (T e , n e ) profiles, from which distributions of ionized, atomic, and molecular gases can be determined. Direct comparison of the dust and gas column mass maps constrained by the HerPlaNS data allows to construct an empirical gas-to-dust mass ratio map, which shows a range of ratios with the median of 195 ± 110. The present analysis yields estimates of the total mass of the shell to be 0.86 M , consisting of 0.54 M of ionized gas, 0.12 M of atomic gas, 0.2 M of molecular gas, and 4 × 10 −3 M of dust grains. These estimates also suggest that the central star of about 1.5 M initial mass is terminating its PN evolution onto the white dwarf cooling track. Conclusions. The HerPlaNS data provide various diagnostics for both the dust and gas components in a spatially resolved manner. In the forthcoming papers of the HerPlaNS series we will explore the HerPlaNS data set fully for the entire sample of 11 PNe.

The Herschel Planetary Nebula Survey (HerPlaNS): A Comprehensive Dusty Photoionization Model of NGC6781

“…Spectroscopically, both PNe show PAH features and pure rotational H 2 lines in their Spitzer/IRS spectra (Phillips et al 2011;Cox et al 2016) as well as rotational-vibrational H 2 emission (e.g., Hiriart 2005;van Hoof et al 2010). Both PNe possess a structure due to a heavy equatorial concentration (i.e., a generic bipolar/barrel shape) viewed nearly poleon (Schwarz & Monteiro 2006;Sahai et al 2012;Ueta et al 2014).…”

Herschel Planetary Nebula Survey (HerPlaNS)★: hydrogen recombination laser lines in Mz 3

“…The FIR to submm spectrum of Mz 3 presented in this paper was obtained by the Herschel Planetary Nebulae Survey (HerPlaNS ; Ueta et al 2014). The survey acquired FIR/submm spectra and broadband images of eleven PNe with the PACS (Photodetector Array Camera and Spectrometer;Poglitsch et al 2010) and SPIRE (Spectral and Photometric Imaging Receiver;Griffin et al 2010) instruments on board the Herschel Space Observatory (Pilbratt et al 2010).…”

“…The data reduction procedure for the HerPlaNS observations is described in Ueta et al (2014). For PACS data, the reduction was performed with HIPE 3 (version 11 4 , calibration release version 44), using the background normalisation PACS spectroscopy pipeline script and following the procedure described in the PACS Data Reduction Guide: Spectroscopy 5 .…”

On the Origin of Morphological Structures of Planetary Nebulae

“…Current mid-infrared imaging of PNe mainly reveals dust in the torus or in the bipolar lobes [29,30]. Although efforts have been made to map the cold dust component by Spitzer [31,32], AKARI [33], and Herschel [34][35][36], the extended cold dust component be truly revealed with high angular resolution, high sensitivity, far infrared imaging with facilities such as SOFIA.…”