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Canadian Involvement in the Herschel Space Telescope Key Program “The Warm and Dense ISM” (WADI). Kevin France & Peter G. Martin (CITA/U of Toronto) for the WADI Consortium. Abstract
“The Warm and Dense ISM” (WADI)
Kevin France & Peter G. Martin (CITA/U of Toronto) for the WADI Consortium
We report on Canadian involvement in the Herschel Space Telescope Guaranteed Time Key Programme `The Warm & Dense ISM' (WADI). WADI explores the roles of UV photons from massive stars and shocks from supernova outflows in shaping the Galactic ISM. WADI will use HIFI and PACS observations to provide a set of far-IR atomic and molecular line diagnostics that can be used as templates for the interpretation of data from more distant star-forming galaxies. CITA is part of the WADI consortium, coordinating the observing strategy and supporting observations of the nearby PDR IC 59. We present an overview of the WADI project and ongoing efforts to obtain complementary imaging and spectral observations of IC 59, from IR to UV wavelengths.
The emission nebula IC 63 is a prototypical object for studies of molecular photoexcitation in the local interstellar medium.
In order to better understand the influence of density structure on
the PDR energy balance and kinematics, we have applied the Canadian WADI time to the nearby cloud IC 59. Both clouds are under the
influence of Cas (B0.5IVe). Comparing IC 59 and IC 63 will
allow us to remove uncertainties about the shape of the illuminating radiation field when modeling the spectral characteristics of these objects.
WADI observations of IC 63/IC 59 are being coordinated by Marco Spaans, with the IC 59 observing strategy being defined at CITA. To date, we have created the Herschel Astronomical Observation Requests (AORs) for IC 59, compiled supporting visible to far-IR observations, and have submitted a proposal to acquire Discretionary Time observations of possible fluorescent H2 emission with FUSE. The AORs target numerous atomic, molecular, and dust emissions, including:
C II, O I, O III, N II, N III, HD, CH, CH+, OH, CO, NH, NH3, several species of H2O, and far-IR dust continuum from 72-210 um. These observations will be complemented by Herschel-SPIRE and PACS imaging as part of the "Evolution of Interstellar Dust" KP.
IC 63 & IC 59
Fig2- PDR models for
H and C abundances across the interface
3.6(B), 5.8(G), 8.0(R) μm
WADI Targets - PDRs
WADI Science Goals
IRAC 8 m
MIPS 24 m
Fig4-Wide field B-band image of the IC63/IC59 system (top), and individual Spitzer-IRAC (left) and MIPS (right) images
Main criteria for classical PDRs are:
- the sources cover a wide range of FUV field intensities
and spectral shapes.
- the sources have a well defined geometry and orientation with
respect to the observer & illuminating star, preferably edge-on.
- high spatial resolution is an asset, favoring nearby sources;
unfortunately closer PDRs tend to have lower UV fields.
- complementary chemical information. All proposed source have been extensively studied with ground-based observations, so that a large set of complementary data is available.
As a reference, we plan to perform complementary observations
of one dense cloud which is exposed to the standard interstellar radiation field only and not influenced by shocks (B68). The list presented above is ordered by the intensity of the UV radiation field, where the value given here is the field at the edge of the clouds, relative to the interstellar radiation field (ISRF; Draine 1978). All of the sources exhibit particular features that further underline the value of their observation. Comparing Carina and NGC7023 shows the impact of the spectral shape of the illuminating field, comparing S140 and Rosette shows the influence of X-rays on the PDR chemistry, and Ced201 will provide clues to time-dependent PDR chemistry due to the high proper motion of the illuminating source.
Fig5-Overlay of the Spitzer-IRS mapping observations (above) and the IRS spectra (right)
FUSE Discretionary Time
IC 59 - H2 Fluorescence
Image courtesy of David Teyssier
Herschel/WADI -- Consortium members:
Volker Ossenkoph-PI KOSMA/SRON – DE/NL
M. Roellig KOSMA-DE
M. Gerin LERMA – FR R. Simon KOSMA-DE
A. Gusten MPIR-DE M. Spaans Kapteyn-NL
A. Benz ETH-CH J. Stutzki KOSMA-DE
F. Boulanger IAS-FR D. Teyssier ESA-ES
A. Fuente OAN-ES H. Yorke JPL-US
A. Harris UMD-US O. Berne CESR-FR
Ch. Joblin CNRS-FR J. LeBourlot CNRS-FR
Th. Klein MPIR-DE S. Bruderer ETH-CH
S. Lord JPL-US K. France CITA-CAN
C. Kramer KOSMA-DE J. Coicoechea LERMA-FR
P. G. Martin CITA – CAN B. Mookerjea UMD-US
J. Martin-Pintado CSIC-ES F. LePetit LUTH-FR
D. Neufeld JHU – US D. Poelman Kapteyn-NL
S. Philipp MPIR-DE R. Rizzo UEM-ES
T. Phillips JPL-US
B + 8 m + 24 m
Fig3 – Sample Herschel AORs for IC 59. The blue stripes are HIFI maps (CH-536 and CII-1900 GHz), the green and red squares are PACS, and the cyan squares are proposed for FUSE
For More Information:
Fig1 – Example of typical HIFI mapping strategy.
Cuts sample the PDR interface as they cross from the HII region onto the molecular cloud.
Fig6– Fluorescent H2 emission in IC 63 from HUT (left) and FUSE (right)