Why Galaxies Care About AGB Stars: A Continuing Challenge through Cosmic Time Proceedings IAU Symposium No. 343, 2019 F. Kerschbaum, M. Groenewegen & H. Olofsson, eds. c  International Astronomical Union 2019 doi:10.1017/S1743921318006385 Herschel Planetary Nebula Survey Plus (HerPlaNS+) Toshiya Ueta 1 , Isabel Aleman 2 , Masaaki Otsuka 3 , Katrina Exter 4 and the HerPlaNS consortium 1 University of Denver, Denver, CO 80112, U.S.A. email: toshiya.ueta@du.edu (TU) 2 IAG-USP, University of S˜ ao Paulo, Brazil 3 Okayama Observatory, Kyoto University, Japan 4 KU Leuven, Belgium Abstract. We present the current status update of the Herschel Planetary Nebula Survey Plus project (HerPlaNS+) based on the original General Observer HerPlaNS survey program during the OT1 cycle and the follow-up exhaustive archival search of PN observations using the PACS and SPIRE instruments on-board the Herschel Space Observatory. Keywords. planetary nebulae: general, circumstellar matter, stars: mass loss, infrared: stars, surveys 1. HerPlaNS The original Herschel Planetary Nebula Survey (HerPlaNS) was performed using all available observational modes of the PACS and SPIRE instruments aboard Herschel to investigate the far-IR characteristics of both the dust and gas components of the circumstellar nebulae for a set of 11 high-excitation PNe (Ueta et al. 2014). We obtained (1) broadband maps of the target sources at five far-IR bands, 70, 160, 250, 350, and 500 μm, with rms sensitivities of 0.01–0.1 mJy arcsec -2 (0.4–4 MJy sr -1 ); (2) 5 × 5 IFU spectral cubes of 51–220 μm covering roughly a 50 ′′ × 50 ′′ field at multiple positions in the target sources, with rms sensitivities of 0.1–1 mJy arcsec -2 (4–40 MJy sr -1 ) per wavelength bin; and (3) a sparsely sampled spectral array of 194–672 μm covering roughly a3 ′ field at multiple positions in the target sources, with rms sensitivities of 0.001– 0.1 mJy arcsec -2 (0.04–4 MJy sr -1 ) per wavelength bin. A quick demonstration of the intended analyses using NGC 6781 as an example yielded the following: (1) the spectral fitting of the broadband images indicated that dust grains are composed mostly of amorphous-carbon based material (i.e., the power-law emissivity index of β ≈ 1) of the temperature between 26 and 40 K; (2) the spatially-resolved plasma diagnostics using line ratios such as [O iii] 52/88 μm and [N ii] 122/205 μm resulted in the electron density and temperature (n e ,T e ) and ionic/elemental/relative abundance pro- files exhibiting variations along the radial direction in the equatorial plane of this nearly pole-on bipolar nebula; and (3) the direct comparison between the above results allowed us to derive an empirical gas-to-dust mass ratio distribution projected roughly to the equatorial plane of this nebula, showing variation of the ratio from 550 at the inner edge of the nebula waist to 100 at the detected outer edge with the average ratio being 195 ± 110. This demonstration signified the importance of direct and purely empirical comparison between the gas and dust components with PNe, especially in a spatially-resolved manner, to account for the amount of matter and energetics in these nebulae. 518 https://doi.org/10.1017/S1743921318006385 Published online by Cambridge University Press