Modeling water emission from low-mass protostellar envelopes
arXiv:0805.0772 · doi:10.1051/0004-6361:200809426
Abstract
Within low-mass star formation, water vapor plays a key role in the chemistry and energy balance of the circumstellar material. The Herschel Space Observatory will open up the possibility to observe water lines originating from a wide range of excitation energies.Our aim is to simulate the emission of rotational water lines from envelopes characteristic of embedded low-mass protostars. A large number of parameters that influence the water line emission are explored: luminosity, density,density slope and water abundances.Both dust and water emission are modelled using full radiative transfer in spherical symmetry. The temperature profile is calculated for a given density profile. The H2O level populations and emission profiles are in turn computed with a non-LTE line code. The results are analyzed to determine the diagnostic value of different lines, and are compared with existing observations. Lines can be categorized in: (i) optically thick lines, including ground-state lines, mostly sensitive to the cold outer part; (ii) highly excited (E_u>200-250 K) optically thin lines sensitive to the abundance in the hot inner part; and (iii) lines which vary from optically thick to thin depending on the abundances. Dust influences the emission of water significantly by becoming optically thick at the higher frequencies, and by pumping optically thin lines. A good physical model of a source, including a correct treatment of dust, is a prerequisite to infer the water abundance structure and possible jumps at the evaporation temperature from observations. The inner warm (T>100 K) envelope can be probed byhighly-excited lines, while a combination of excited and spectrally resolved ground state lines probes the outer envelope. Observations of H218O lines, although weak, provide even stronger constraints on abundances.
17 pages with an online appendix of 6 pages. Accepted by A&A. Several figures are too large for astro-ph. These can be downloaded from http://www.strw.leidenuniv.nl/~kempen/water.php
References in corpus (34)
- An atomic and molecular database for analysis of submillimetre line observations
- Self-similarity and scaling behavior of IR emission from radiatively heated dust: I. Theory
- Physical structure and CO abundance of low-mass protostellar envelopes
- Thermal Desorption of Water-Ice in the Interstellar Medium
- Structure and Evolution of the Envelopes of Deeply Embedded Massive Young Stars
- Does IRAS 16293-2422 have a hot core? Chemical inventory and abundance changes in its protostellar environment
- PROSAC: A Submillimeter Array Survey of Low-Mass Protostars. I. Overview of Program: Envelopes, Disks, Outflows and Hot Cores
- Molecular Inventories and Chemical Evolution of Low-mass Protostellar Envelopes
- Tracing the Mass during Low-Mass Star Formation. I. Submillimeter Continuum Observations
- Mapping ices in protostellar environments on 1000 AU scales: Methanol-rich ice in the envelope of Serpens SMM 4
- Evolutionary Signatures in the Formation of Low-Mass Protostars
- The H2CO abundance in the inner warm regions of low mass protostellar envelopes
- Water Abundance in Molecular Cloud Cores
- Quasi-classical rate coefficient calculations for the rotational (de)excitation of H2O by H2
- Numerical methods for non-LTE line radiative transfer: Performance and convergence characteristics
- 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
- Imaging chemical differentiation around the low-mass protostar L483-mm
- Thermal Water Vapor Emission from Shocked Regions in Orion
- Water in the envelopes and disks around young high-mass stars
- H2CO and CH3OH abundances in the envelopes around low-mass protostars
- HDO abundance in the envelope of the solar-type protostar IRAS16293-2422
- Water emission in NGC1333-IRAS4: The physical structure of the envelope
- On the origin of H2CO abundance enhancements in low-mass protostars
- B335: A Laboratory for Astrochemistry in a Collapsing Cloud
- The Environment and Nature of the Class I Protostar Elias 29: Molecular Gas Observations and the Location of Ices
- Water maser variability over 20 years in a large sample of star-forming regions: the complete database
- The excitation of water in the S140 photon dominated region
- The effect of a strong external radiation field on protostellar envelopes in Orion
- Sensitive Limits on the Water Abundance in Cold Low Mass Molecular Cores
- A Survey of 557 GHz Water Vapor Emission in the NGC 1333 Molecular Cloud
- Modelling submillimetre spectra of the protostellar infall candidates NGC1333-IRAS2 and Serpens SMM4
- Observations of Water Masers in the NGC 1333 IRAS 4 Region
- Modeling the water line emission from the high-mass star-forming region AFGL2591
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- Photodesorption of Ices II: H2O and D2O
- Molecules with ALMA at Planet-forming Scales (MAPS) I: Program Overview and Highlights
- Water in star-forming regions with Herschel (WISH): II. Evolution of 557 GHz 110-101 emission in low-mass protostars
- Water in star-forming regions (WISH): Physics and chemistry from clouds to disks as probed by Herschel spectroscopy
- A study of deuterated water in the low-mass protostar IRAS16293-2422
- APEX-CHAMP+ high-J CO observations of low-mass young stellar objects: I. The HH 46 envelope and outflow
- Hot water in the inner 100 AU of the Class 0 protostar NGC1333 IRAS2A
- Candidate Water Vapor Lines to Locate the Snowline through High-dispersion Spectroscopic Observations. III. Submillimeter and Lines
- 183 GHz HO maser emission around the low-mass protostar Serpens SMM1