Line profiles of water for the photon dominated region and embedded sources in the S140 region

Abstract

A radiative transfer method for the treatment of molecular lines is presented. We apply this method to previous SWAS and ISO observations of water vapor in the source S140 in order to make models to plan for, and to interpret, HIFI data. Level populations are calculated with the use of a three-dimensional (multi-zone) escape probability method and with a long characteristic code that uses Monte Carlo techniques with fixed directions. Homogeneous and inhomogeneous models are used to compute the differences between water line profiles across the S140 region. We find that when an outflow or infall velocity field with a gradient of a few kms^{-1} is adopted, line profiles with a FWHM of 6 kms^{-1} are found, in agreement with observations. Inhomogeneous models are favoured to produce a single-peaked line profile. When zooming in on smaller regions within the PDR, the shapes of the line profiles start to differ due to the different temperature and density distributions there. The embedded sources are traced by high excitation lines of, e.g., 3_{21}-2_{21}, 3_{03}-2_{12}, 2_{12}-1_{01} and 2_{20}-1_{11}. The computed intensities are roughly consistent with existing ISO observations. Water emission in a PDR source like S140 requires a combination of a pure PDR and an embedded source in order to match the observations. Because of its good angular resolution, HIFI will be able to distinguish between a dense star forming region or a more diffuse gas component. It is therefore important for future observing programs to consider both in their predictions of the emission characteristics of water in these environments.

References in corpus (11)

• Structure and Evolution of the Envelopes of Deeply Embedded Massive Young Stars
• ISO spectroscopy of gas and dust: from molecular clouds to protoplanetary disks
• Evolution of Chemistry and Molecular Line Profile during Protostellar Collapse
• Water Abundance in Molecular Cloud Cores
• Sulphur chemistry in the envelopes of massive young stars
• Probing the Early Stages of Low-Mass Star Formation in LDN 1689N: Dust and Water in IRAS 16293-2422A, B, and E
• Models for Dense Molecular Cloud Cores
• The excitation of water in the S140 photon dominated region
• A New Exact Method for Line Radiative Transfer
• O-bearing Molecules in Carbon-rich Proto-Planetary Objects
• The Abundance and Emission of H2O and O2 in Clumpy Molecular Clouds

Cited by in corpus (22)

• Radiative transfer models of mid-infrared H2O lines in the Planet-forming Region of Circumstellar Disks
• A Theory for the Excitation of CO in Star Forming Galaxies
• Sub-mm Emission Line Deep Fields: CO and [CII] Luminosity Functions out to z = 6
• Water vapor emission reveals a highly obscured, star forming nuclear region in the QSO host galaxy APM08279+5255 at z=3.9
• Hot and cool water in Herbig Ae protoplanetary disks. A challenge for Herschel
• Molecular line radiative transfer in protoplanetary disks: Monte Carlo simulations versus approximate methods
• On the Detection of High Redshift Black Holes with ALMA through CO and H2 Emission
• Probing high-redshift quasars with ALMA. I. Expected observables and potential number of sources
• The nature of the ISM in galaxies during the star-formation activity peak of the Universe
• HIFI Spectroscopy of ${\mathrm{H}}_2\mathrm{O}$ submm Lines in Nuclei of Actively Star Forming Galaxies
• Star formation near an obscured AGN: Variations in the initial mass function
• Rotational Line Emission from Water in Protoplanetary Disks
• The Structure and Dynamics of an AGN Torus: CO Line Predictions for ALMA from 3D Hydrodynamical Simulations with X-ray Driven Chemistry
• The Thermodynamics of Molecular Cloud Fragmentation: Star Formation Under Non-Milky Way Conditions
• Physical Characteristics of a Dark Cloud in an Early Stage of Star Formation toward NGC 7538: an Outer Galaxy Infrared Dark Cloud?
• The fine structure line deficit in S 140
• Temperatures of dust and gas in S~140
• Water and ammonia abundances in S140 with the Odin satellite
• The interpretation of water emission from dense interstellar clouds
• Modeling the water line emission from the high-mass star-forming region AFGL2591
• The Dense Gas in the Central Kiloparsec of NGC 6946
• Weak, extended water vapor emission in the Horsehead nebula