Konrad Zuse und die ETH Zürich

Bruderer, Herbert

doi:10.1007/s00287-011-0573-4

Cited by 4 publications

(3 citation statements)

References 3 publications

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“…For example, the CH 536 GHz triplet is often obtained together with the o-H 2 18 O 1 10 À 1 01 548 GHz line and the H 2 O þ 1 11 À 0 00 1115 GHz line with the p-H 2 O 1 11 À 0 00 1113 GHz line. Line frequencies have been collected, and in some cases first predicted, by Bruderer (2006).…”

Section: Source and Line Selectionmentioning

confidence: 99%

Water in Star-forming Regions with theHerschel Space Observatory(WISH). I. Overview of Key Program and First Results

Dishoeck¹,

Kristensen²,

Benz³

et al. 2011

Publications of the Astronomical Society of the Pacific

212

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ABSTRACT. Water In Star-forming regions with Herschel (WISH) is a key program on the Herschel Space Observatory designed to probe the physical and chemical structures of young stellar objects using water and related molecules and to follow the water abundance from collapsing clouds to planet-forming disks. About 80 sources are targeted, covering a wide range of luminosities-from low (<1 L ⊙ ) to high (>10 5 L ⊙ )-and a wide range of evolutionary stages-from cold prestellar cores to warm protostellar envelopes and outflows to disks around young stars. Both the HIFI and PACS instruments are used to observe a variety of lines of H 2 O, H 2 18 O and chemically related species at the source position and in small maps around the protostars and selected outflow positions. In addition, high-frequency lines of CO, 13 CO, and C 18 O are obtained with Herschel and are complemented by ground-based observations of dust continuum, HDO, CO and its isotopologs, and other molecules to ensure 16 PACIFIC, 123:138-170, 2011 February © 2011. The Astronomical Society of the Pacific. All rights reserved. Printed in U.S.A. a self-consistent data set for analysis. An overview of the scientific motivation and observational strategy of the program is given, together with the modeling approach and analysis tools that have been developed. Initial science results are presented. These include a lack of water in cold gas at abundances that are lower than most predictions, strong water emission from shocks in protostellar environments, the importance of UV radiation in heating the gas along outflow walls across the full range of luminosities, and surprisingly widespread detection of the chemically related hydrides OH þ and H 2 O þ in outflows and foreground gas. Quantitative estimates of the energy budget indicate that H 2 O is generally not the dominant coolant in the warm dense gas associated with protostars. Very deep limits on the cold gaseous water reservoir in the outer regions of protoplanetary disks are obtained that have profound implications for our understanding of grain growth and mixing in disks.

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Section: Source and Line Selectionmentioning

confidence: 99%

Water in Star-forming Regions with theHerschel Space Observatory(WISH). I. Overview of Key Program and First Results

Dishoeck¹,

Kristensen²,

Benz³

et al. 2011

Publications of the Astronomical Society of the Pacific

212

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“…First, it presents details of the implementation of the model and second, it compares of results with other codes and benchmark problems. The model is based on those of Bruderer et al (2009bBruderer et al ( ,a, 2010 and Bruderer (2010), although it contains several improvements. The structure of the model is summarized in Fig.…”

Section: Appendix A: Details Of the Models And Benchmark Testsmentioning

confidence: 99%

The warm gas atmosphere of the HD 100546 disk seen byHerschel

Bruderer

Dishoeck

Doty

et al. 2012

A&A

255

454

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Context. With the Herschel Space Observatory, lines of simple molecules (C + , O, and high-J lines of CO, J up 14) have been observed in the atmosphere of protoplanetary disks. When combined with ground-based data on [C i], all principle forms of carbon can be studied. These data allow us to test model predictions for the main carbon-bearing species and verify the presence of a warm surface layer. The absence of neutral carbon [C i], which is predicted by models to be strong, can then be interpreted together with ionized carbon [C ii] and carbon monoxide. Aims. We study the gas temperature, excitation, and chemical abundance of the simple carbon-bearing species C, C + , and CO, as well as O by the method of chemical-physical modeling. Using the models, we explore the sensitivity of the lines to the entering parameters and constrain the region from which the line radiation emerges. Methods. Numerical models of the radiative transfer in the lines and dust are used together with a chemical network simulation and a calculation of the gas energetics to obtain the gas temperature. We present our new model, which is based on our previous models but includes several improvements that we report in detail, together with the results of benchmark tests. Results. A model of the disk around the Herbig Be star HD 100546 is able to reproduce the CO ladder together with the atomic finestructure lines of [O i] and either [C i] or [C ii]. We find that the high-J lines of CO can only be reproduced by a warm atmosphere with T gas T dust . The low-J lines of CO, observable from the ground, are dominated by the outer disk with a radius of several 100 AU, while the high-J CO observable with Herschel-PACS are dominated from regions within some tens of AU. The spectral profiles of high-J lines of CO are predicted to be broader than those of the low-J lines. We study the effect of several parameters including the size of the disk, the gas mass of the disk, the PAH abundance and distribution, and the amount of carbon in the gas phase. Conclusions. The main conclusions of our work are (i) only a warm atmosphere with T gas T dust can reproduce the CO ladder. (ii) The CO ladder together with [O i] and the upper limit to [C i] can be reproduced by models with a high gas/dust ratio and a low abundance of volatile carbon. These models however produce too small amounts of [C ii]. Models with a low gas/dust ratio and more volatile carbon also reproduce CO and [O i], are in closer agreement with observations of [C ii], but overproduce [C i]. Owing to the uncertain origin of the [C ii] emission, we prefer the high gas/dust ratio models, indicating a low abundance of volatile carbon.

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“…Preparing for this project, Stäuber et al (2004Stäuber et al ( , 2005 showed that hydrides may be enhanced in star-forming regions affected by far UV and/or X-ray irradiation. In a second step, optimal lines were selected using catalogued data in the available databases or computed from measured molecular constants (Bruderer 2006).…”

Section: Introductionmentioning

confidence: 99%

Hydrides in young stellar objects: Radiation tracers in a protostar-disk-outflow system

Benz¹,

Bruderer²,

Dishoeck

et al. 2010

A&A

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Context. Hydrides of the most abundant heavier elements are fundamental molecules in cosmic chemistry. Some of them trace gas irradiated by UV or X-rays. Aims. We explore the abundances of major hydrides in W3 IRS5, a prototypical region of high-mass star formation. Methods. W3 IRS5 was observed by HIFI on the Herschel Space Observatory with deep integration ( 2500 s) in 8 spectral regions. Results. The target lines including CH, NH, H 3 O + , and the new molecules SH + , H 2 O + , and OH + are detected. The H 2 O + and OH + J = 1−0 lines are found mostly in absorption, but also appear to exhibit weak emission (P-Cyg-like). Emission requires high density, thus originates most likely near the protostar. This is corroborated by the absence of line shifts relative to the young stellar object (YSO). In addition, H 2 O + and OH + also contain strong absorption components at a velocity shifted relative to W3 IRS5, which are attributed to foreground clouds. Conclusions. The molecular column densities derived from observations correlate well with the predictions of a model that assumes the main emission region is in outflow walls, heated and irradiated by protostellar UV radiation.

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Konrad Zuse und die ETH Zürich

Cited by 4 publications

References 3 publications

Water in Star-forming Regions with theHerschel Space Observatory(WISH). I. Overview of Key Program and First Results

Water in Star-forming Regions with theHerschel Space Observatory(WISH). I. Overview of Key Program and First Results

The warm gas atmosphere of the HD 100546 disk seen byHerschel

Hydrides in young stellar objects: Radiation tracers in a protostar-disk-outflow system

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