Millimeter Observations and Modeling of the AB Aurigae System

Semenov, D.; Pavlyuchenkov, Ya. N.; Schreyer, K.; Henning, Th.; Dullemond, C. P.; Bacmann, A.

doi:10.1086/427725

Cited by 65 publications

(87 citation statements)

References 73 publications

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“…Both codes have been intensively utilized in various studies of molecular cloud and protoplanetary disk chemistry, e.g. the influence of the reaction rate uncertainties on the results of chemical modeling of cores (Vasyunin et al 2004;Wakelam et al 2005Wakelam et al , 2006 and disks (Vasyunin et al 2008), modeling of the disk chemical evolution with turbulent diffusion (Semenov et al 2006;Hersant et al 2009), interpretation of interferometric data (Semenov et al 2005;Dutrey et al 2007;Schreyer et al 2008;Henning et al 2010), and predictions for ALMA . Both codes are optimized to model timedependent evolution of a large set of gas-phase and surface species linked through thousands of gas-phase, gas-grain, and surface processes.…”

Section: Heidelberg and Bordeaux Chemical Codesmentioning

confidence: 99%

“…Several compilations of surface reactions have also been presented (e.g., Allen & Robinson 1977;Tielens & Hagen 1982;Hasegawa et al 1992;Hasegawa & Herbst 1993;Garrod & Herbst 2006). The detailed physics and chemistry processes incorporated in the modern theoretical models allow predicting and, at last, fitting to the observational interferometric data, such as molecular line maps of protoplanetary disks and molecular clouds (e.g., Semenov et al 2005;Dutrey et al 2007;Goicoechea et al 2009;Panić & Hogerheijde 2009;Henning et al 2010). However, with the advent of forthcoming high-sensitivity, high-resolution instruments like ALMA, ELT, and JWST, the degree of complexity of these models will have to be increased and their foundations be critically re-evaluated to match the quality of the data (e.g., Asensio Ramos et al 2007;Lellouch 2008;Semenov et al 2008).…”

Section: Introductionmentioning

confidence: 99%

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Chemistry in disks

Semenov

Hersant

Wakelam

et al. 2010

A&A

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Context. We describe and benchmark two sophisticated chemical models developed by the Heidelberg and Bordeaux astrochemistry groups. Aims. The main goal of this study is to elaborate on a few well-described tests for state-of-the-art astrochemical codes covering a range of physical conditions and chemical processes, in particular those aimed at constraining current and future interferometric observations of protoplanetary disks. Methods. We considered three physical models: a cold molecular cloud core, a hot core, and an outer region of a T Tauri disk. Our chemical network (for both models) is based on the original gas-phase osu_03_2008 ratefile and includes gas-grain interactions and a set of surface reactions for the H-, O-, C-, S-, and N-bearing molecules. The benchmarking was performed with the increasing complexity of the considered processes: (1) the pure gas-phase chemistry, (2) the gas-phase chemistry with accretion and desorption, and (3) the full gas-grain model with surface reactions. The chemical evolution is modeled within 10 9 years using atomic initial abundances with heavily depleted metals and hydrogen in its molecular form. Results. The time-dependent abundances calculated with the two chemical models are essentially the same for all considered physical cases and for all species, including the most complex polyatomic ions and organic molecules. This result, however, required a lot of effort to make all necessary details consistent through the model runs, e.g., definition of the gas particle density, density of grain surface sites, or the strength and shape of the UV radiation field. Conclusions. The reference models and the benchmark setup, along with the two chemical codes and resulting time-dependent abundances are made publicly available on the internet. This will facilitate and ease the development of other astrochemical models and provide nonspecialists with a detailed description of the model ingredients and requirements to analyze the cosmic chemistry as studied, e.g., by (sub-) millimeter observations of molecular lines.

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Section: Heidelberg and Bordeaux Chemical Codesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chemistry in disks

Semenov

Hersant

Wakelam

et al. 2010

A&A

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“…This procedure provides flat baselines, which are essential for detecting weak and wide lines toward compact sources, which is the case for the lines arising in circumstellar disks. In the case of AB Aur, the disk is still immersed in the parent cloud whose emission extends farther than the wobbler throw (see Semenov et al 2005). Then, at the velocities of the ambient cloud the detected emission is just the ON-OFF balance without any physical interpretation (remember that the OFF position is moving in the sky during the source tracking).…”

Section: Observationsmentioning

confidence: 99%

Molecular content of the circumstellar disk in AB Aurigae

Fuente

Cernicharo

Agúndez

et al. 2010

A&A

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Aims. Very few molecular species have been detected in circumstellar disks surrounding young stellar objects. We are carrying out an observational study of the chemistry of circumstellar disks surrounding T Tauri and Herbig Ae stars. First results of this study are presented in this note. Methods. We used the EMIR receivers recently installed at the IRAM 30 m telescope to carry out a sensitive search for molecular lines in the disks surrounding AB Aur, DM Tau, and LkCa 15. Results. We detected lines of the molecules HCO + , CN, H 2 CO, SO, CS, and HCN toward AB Aur. In addition, we tentatively detected DCO + and H 2 S lines. The line profiles suggest that the CN, HCN, H 2 CO, CS, and SO lines arise in the disk. This makes it the first detection of SO in a circumstellar disk. We have unsuccessfully searched for SO toward DM Tau and LkCa 15, and for c-C 3 H 2 toward AB Aur, DM Tau, and LkCa 15. Our upper limits show that contrary to all molecular species observed so far, SO is not as abundant in DM Tau as it is in AB Aur.Conclusions. Our results demonstrate that the disk associated with AB Aur is rich in molecular species. Our chemical model shows that the detection of SO is consistent with that expected from a very young disk where the molecular adsorption onto grains does not yet dominate the chemistry.

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“…The chemical and temperature profiles of discs determine the chemical composition of the gas that will eventually be incorporated into a planet's atmosphere, once a solid ∼10 Earth mass core is formed (Armitage 2010). Millimetre observations of molecules in discs probe the outer cold part (Dutrey et al 1997;van Zadelhoff et al 2001;Thi et al 2004;Semenov et al 2005;Henning et al 2010;Öberg et al 2010, e.g.). Minor species located in the inner disc, such as C 2 H 2 and HCN, were observed with the Spitzer Space Telescope (Carr & Najita 2008;Pascucci & Sterzik 2009;Lahuis et al 2006;Pontoppidan et al 2010)…”

Section: Introductionmentioning

confidence: 99%

Detection of CH⁺emission from the disc around HD 100546

Thi

Ménard

Meeus

et al. 2011

A&A

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Despite its importance in the thermal balance of the gas and in the determination of primeval planetary atmospheres, the chemistry in protoplanetary discs remains poorly constrained with only a handful of detected species. We observed the emission from the disc around the Herbig Be star HD 100546 with the PACS instrument in the spectroscopic mode on board the Herschel Space Telescope as part of the GAS in Protoplanetary Systems (GASPS) programme and used archival data from the DIGIT programme to search for the rotational emission of CH + . We detected in both datasets an emission line centred at 72.16 μm that most likely corresponds to the J = 5−4 rotational emission of CH + . The J = 3−2 and 6−5 transitions are also detected albeit with lower confidence. Other CH + rotational lines in the PACS observations are blended with water lines. A rotational diagram analysis shows that the CH + gas is warm at 323 +2320 −151 K with a mass of ∼3 × 10 −14 −5 × 10 −12 M . We modelled the CH + chemistry with the chemo-physical code ProDiMo using a disc density structure and grain parameters that match continuum observations and near-and mid-infrared interferometric data. The model suggests that CH + is most abundant at the location of the disc rim at 10−13 AU from the star where the gas is warm, which is consistent with previous observations of hot CO gas emission.

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Millimeter Observations and Modeling of the AB Aurigae System

Cited by 65 publications

References 73 publications

Chemistry in disks

Chemistry in disks

Molecular content of the circumstellar disk in AB Aurigae

Detection of CH⁺emission from the disc around HD 100546

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Millimeter Observations and Modeling of the AB Aurigae System

Cited by 65 publications

References 73 publications

Chemistry in disks

Chemistry in disks

Molecular content of the circumstellar disk in AB Aurigae

Detection of CH+emission from the disc around HD 100546

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Detection of CH⁺emission from the disc around HD 100546