The Herschel Planetary Nebula Survey (HerPlaNS) I. Data overview and analysis demonstration with NGC 6781
Journal article, 2014
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-circle dot, consisting of 0.54 M-circle dot of ionized gas, 0.12 M-circle dot of atomic gas, 0.2 M-circle dot of molecular gas, and 4 x 10(-3) M-circle dot of dust grains. These estimates' also suggest that the central star of about 1.5 M-circle dot 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.
planetary nebulae: general
stars: mass-loss
infrared: stars
planetary nebulae
stars: winds
outflows
Author
T. Ueta
University of Denver
JAXA Institute of Space and Astronautical Science
D. Ladjal
University of Denver
K. M. Exter
KU Leuven
M. Otsuka
Academia Sinica
R. Szczerba
Polish Academy of Sciences
N. Siodmiak
Polish Academy of Sciences
I. Aleman
Leiden University
P. A. M. van Hoof
Royal Observatory of Belgium
J. H. Kastner
Rochester Institute of Technology
R. Montez
Vanderbilt University
I. McDonald
Jodrell Bank Centre for Astrophysics
M. Wittkowski
European Southern Observatory (ESO)
C. Sandin
Leibniz Institute for Astrophysics Potsdam
S. Ramstedt
Uppsala University
O. De Marco
Macquarie University
E. Villaver
Universidad Autonoma de Madrid (UAM)
Y. H. Chu
University of Illinois
Wouter Vlemmings
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
Chalmers, Earth and Space Sciences, Onsala Space Observatory
H. Izumiura
National Astronomical Observatory of Japan
R. Sahai
California Institute of Technology (Caltech)
J. A. Lopez
Universidad Nacional Autónoma de México
B. Balick
University of Washington
A. Zijlstra
Jodrell Bank Centre for Astrophysics
Aggm Tielens
Leiden University
R. E. Rattray
University of Denver
E. Behar
Technion – Israel Institute of Technology
E. G. Blackman
University of Rochester
K. Hebden
Jodrell Bank Centre for Astrophysics
J. L. Hora
Harvard-Smithsonian Center for Astrophysics
K. Murakawa
University of Leeds
J. Nordhaus
Rochester Institute of Technology
R. Nordon
Max Planck Society
I. Yamamura
JAXA Institute of Space and Astronautical Science
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 565 A36Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201423395