DIGIT survey of far-infrared lines from protoplanetary disks

Fedele, D.; Bruderer, S.; Dishoeck, E. F. van; Carr, John S.; Herczeg, Gregory J.; Salyk, Colette; Evans, Neal J.; Bouwman, J.; Meeus, G.; Henning, Th.; Green, J.; Najita, J.; Güdel, M.

doi:10.1051/0004-6361/201321118

Cited by 114 publications

(158 citation statements)

References 70 publications

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“…Neal Evans). These spectra show pure rotational transitions of CO with J up from 14 to 49, corresponding to E up between 581 and 6724 K. Detections of O , C , OH, H 2 O, and CH + are reported in a companion paper by Fedele et al (2013;Paper I). In Sect.…”

Section: Introductionmentioning

confidence: 76%

DIGIT survey of far-infrared lines from protoplanetary discs

Meeus

Salyk

Bruderer

et al. 2013

A&A

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CO is an important component of a protoplanetary disc as it is one of the most abundant gas phase species. Furthermore, observations of CO transitions can be used as a diagnostic of the gas, tracing conditions in both the inner and outer disc. We present Herschel/PACS spectroscopy of a sample of 22 Herbig Ae/Be (HAEBEs) and eight T Tauri stars (TTS), covering the pure rotational CO transitions from J = 14 → 13 up to J = 49 → 48. CO is detected in only five HAEBEs, namely AB Aur, HD 36112, HD 97048, HD 100546, and IRS 48, and in four TTS, namely AS 205, S CrA, RU Lup, and DG Tau. The highest transition detected is J = 36 → 35 with E up of 3669 K, seen in HD 100546 and DG Tau. We construct rotational diagrams for the discs with at least three CO detections to derive T rot and find average temperatures of 270 K for the HAEBEs and 485 K for the TTS. The HD 100546 star requires an extra temperature component at T rot ∼ 900-1000 K, suggesting a range of temperatures in its disc atmosphere, which is consistent with thermo-chemical disc models. In HAEBEs, the objects with CO detections all have flared discs in which the gas and dust are thermally decoupled. We use a small model grid to analyse our observations and find that an increased amount of flaring means higher line flux, as it increases the mass in warm gas. CO is not detected in our flat discs as the emission is below the detection limit. We find that HAEBE sources with CO detections have high L UV and strong PAH emission, which is again connected to the heating of the gas. In TTS, the objects with CO detections are all sources with evidence of a disc wind or outflow. For both groups of objects, sources with CO detections generally have high UV luminosity (either stellar in HAEBEs or due to accretion in TTS), but this is not a sufficient condition for the detection of the far-IR CO lines.

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Section: Introductionmentioning

confidence: 76%

DIGIT survey of far-infrared lines from protoplanetary discs

Meeus

Salyk

Bruderer

et al. 2013

A&A

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“…Cooler H 2 O and OH have been detected somewhat further out and deeper into the disk with Herschel-PACS in a few sources 230,231 . The bulk of the cold water reservoir has been revealed by Herschel-HIFI in two disks.…”

Section: Protoplanetary Disksmentioning

confidence: 99%

Astrochemistry of dust, ice and gas: introduction and overview

Dishoeck

Ewine²

2014

Faraday Discuss.

138

102

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A brief introduction and overview of the astrochemistry of dust, ice and gas and their interplay is presented, aimed at non-specialists. The importance of basic chemical physics studies of critical reactions is illustrated through a number of recent examples. Such studies have also triggered new insight into chemistry, illustrating how astronomy and chemistry can enhance each other. Much of the chemistry in star- and planet-forming regions is now thought to be driven by gas-grain chemistry rather than pure gas-phase chemistry, and a critical discussion of the state of such models is given. Recent developments in studies of diffuse clouds and PDRs, cold dense clouds, hot cores, protoplanetary disks and exoplanetary atmospheres are summarized, both for simple and more complex molecules, with links to papers presented in this volume. In spite of many lingering uncertainties, the future of astrochemistry is bright: new observational facilities promise major advances in our understanding of the journey of gas, ice and dust from clouds to planets.Comment: Introductory paper for Faraday Discussions 168 conference, April 201

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“…1, van der Marel et al 2013a) and in the following we will assume that both the mid-infrared and (sub)millimeter continuum emission come from an outer disk located at a radius >60 AU. The far-infrared continuum (60−180 μm), observed by Herschel (Fedele et al 2013), is not spatially resolved and it is unknown whether it is ring-like or lopsided. For our modeling, we adopt the physical structure suggested by Andrews et al (2011), as implemented by Bruderer (2013).…”

Section: Disk Structurementioning

confidence: 99%

Gas structure inside dust cavities of transition disks: Ophiuchus IRS 48 observed by ALMA

Bruderer

Marel

Dishoeck

et al. 2014

A&A

136

196

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Context. Transition disks are recognized by the absence of emission of small dust grains inside a radius of up to several 10s of AUs. Owing to the lack of angular resolution and sensitivity, the gas content of these dust holes has not yet been determined, but is of importance for constraining the mechanism leading to the dust holes. It is thought that transition disks are currently undergoing the process of dispersal, setting an end to the giant planet formation process. Aims. We present new high-resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) of gas lines towards the transition disk Oph IRS 48 previously shown to host a large dust trap. The ALMA telescope has detected the J = 6−5 line of 12 CO and C 17 O around 690 GHz (434 μm) at a resolution of ∼0.25 corresponding to ∼30 AU (FWHM). The observed gas lines are used to set constraints on the gas surface density profile. Methods. New models of the physical-chemical structure of gas and dust in Oph IRS 48 are developed to reproduce the CO line emission together with the spectral energy distribution and the VLT-VISIR 18.7 μm dust continuum images. Integrated intensity cuts and the total spectrum from models having different trial gas surface density profiles are compared to observations. The main parameters varied are the drop in gas surface density inside the dust-free cavity with a radius of 60 AU and inside the gas-depleted innermost 20 AU. Using the derived surface density profiles, predictions for other CO isotopologues are made, which can be tested by future ALMA observations of the object. Results. From the ALMA data we find a total gas mass of the disk of 1.4 × 10 −4 M . This gas mass yields a gas-to-dust ratio of ∼10, but with considerable uncertainty. Inside 60 AU, the gas surface density drops by a factor of ∼12 for an assumed surface density slope of γ = 1 (Σ ∝ r −γ ). Inside 20 AU, the gas surface density drops by a factor of at least 110. The drops are measured relative to the extrapolation to small radii of the surface density law at radii >60 AU. The inner radius of the gas disk at 20 AU can be constrained to better than ±5 AU. Conclusions. The derived gas surface density profile points to the clearing of the cavity by one or more massive planets/companions rather than just photoevaporation or grain-growth.

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DIGIT survey of far-infrared lines from protoplanetary disks

Cited by 114 publications

References 70 publications

DIGIT survey of far-infrared lines from protoplanetary discs

DIGIT survey of far-infrared lines from protoplanetary discs

Astrochemistry of dust, ice and gas: introduction and overview

Gas structure inside dust cavities of transition disks: Ophiuchus IRS 48 observed by ALMA

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