An atomic and molecular database for analysis of submillimetre line observations

Schöier, F. L.; Tak, F. F. S. van der; Dishoeck, E. F. van; Black, J. H.

doi:10.1051/0004-6361:20041729

Cited by 1,420 publications

(1,388 citation statements)

References 106 publications

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“…Table B.2 reports the atomic and molecular data of the transitions detected in this paper. Molecular data are taken from the LAMDA database (Schöier et al 2005). 5.9 ± 0.7 8.9 ± 0.7 10.6 ± 0.7 10.4 ± 0.7 2.6 ± 0.4 3.8 ± 0.4 4.7 ± 0.8 4.7 ± 0.8 AS 205…”

Section: Resultsmentioning

confidence: 99%

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DIGIT survey of far-infrared lines from protoplanetary disks

Fedele

Bruderer

Dishoeck

et al. 2013

A&A

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114

146

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We present far-infrared (50−200 μm) spectroscopic observations of young pre-main-sequence stars taken with Herschel/PACS as part of the DIGIT key project. The sample includes 16 Herbig AeBe and 4 T Tauri sources observed in SED mode covering the entire spectral range. An additional 6 Herbig AeBe and 4 T Tauri systems have been observed in SED mode with a limited spectral coverage. Multiple atomic fine structure and molecular lines are detected at the source position:The most common feature is the [O i] 63 μm line detected in almost all of the sources, followed by OH. In contrast with CO, OH is detected toward both Herbig AeBe groups (flared and non-flared sources). An isothermal LTE slab model fit to the OH lines indicates column densities of 10 13 < N OH < 10 16 cm −2 , emitting radii 15 < r < 100 AU and excitation temperatures 100 < T ex < 400 K. We used the non-LTE code RADEX to verify the LTE assumption. High gas densities (n ≥ 10 10 cm −3 ) are needed to reproduce the observations. The OH emission thus comes from a warm layer in the disk at intermediate stellar distances. Warm H 2 O emission is detected through multiple lines toward the T Tauri systems AS 205, DG Tau, S CrA and RNO 90 and three Herbig AeBe systems HD 104237, HD 142527, HD 163296 (through line stacking). Overall, Herbig AeBe sources have higher OH/H 2 O abundance ratios across the disk than do T Tauri disks, from near-to far-infrared wavelengths. Far-infrared CH + emission is detected toward HD 100546 and HD 97048. The slab model suggests moderate excitation (T ex ∼ 100 K) and compact (r ∼ 60 AU) emission in the case of HD 100546.Off-source [O i] emission is detected toward DG Tau, whose origin is likely the outflow associated with this source. The [C ii] emission is spatially extended in all sources where the line is detected. This suggests that not all [C ii] emission is associated with the disk and that there is a substantial contribution from diffuse material around the young stars. The flux ratios of the atomic fine structure linesare analyzed with PDR models and require high gas density (n 10 5 cm −3 ) and high UV fluxes (G o ∼ 10 3 −10 7 ), consistent with a disk origin for the oxygen lines for most of the sources.

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Section: Resultsmentioning

confidence: 99%

“…The molecular data are from the LAMDA database (Schöier et al 2005). The number of emitting molecules is…”

Section: Slab Modelmentioning

confidence: 99%

DIGIT survey of far-infrared lines from protoplanetary disks

Fedele

Bruderer

Dishoeck

et al. 2013

A&A

Self Cite

114

146

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“…images, spectra) we combined our Cloudy models with the line radiative transfer codes RADMC-3D (Dullemond 2012) and LIME (Brinch & Hogerheijde 2010). Both codes take account of the optical thickness of lines in each direction and for both codes we use the LAMDA database (Schöier et al 2005) to set the Einstein coefficients, transition energies or collision rates. For C I and O I, the optical depth can be a lot higher than unity whilst for C II it only reaches values close to unity in the innermost parts.…”

Section: Emission Linesmentioning

confidence: 99%

A self-consistent model for the evolution of the gas produced in the debris disc of β Pictoris

Kral¹,

Wyatt²,

Carswell³

et al. 2016

Mon. Not. R. Astron. Soc.

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This paper presents a self-consistent model for the evolution of gas produced in the debris disc of β Pictoris. Our model proposes that atomic carbon and oxygen are created from the photodissociation of CO, which is itself released from volatile-rich bodies in the debris disc due to grain-grain collisions or photodesorption. While the CO lasts less than one orbit, the atomic gas evolves by viscous spreading resulting in an accretion disc inside the parent belt and a decretion disc outside. The temperature, ionisation fraction and population levels of carbon and oxygen are followed with the photodissociation region model Cloudy, which is coupled to a dynamical viscous α model. We present new gas observations of β Pic, of C I observed with APEX and O I observed with Herschel, and show that these along with published C II and CO observations can all be explained with this new model. Our model requires a viscosity α > 0.1, similar to that found in sufficiently ionised discs of other astronomical objects; we propose that the magnetorotational instability is at play in this highly ionised and dilute medium. This new model can be tested from its predictions for high resolution ALMA observations of C I. We also constrain the water content of the planetesimals in β Pic. The scenario proposed here might be at play in all debris discs and this model could be used more generally on all discs with C, O or CO detections.

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“…Additionally the molecular properties for CO are taken from the Leiden Atomic and Molecular Database (Schöier et al 2005). The collisional excitation rates that we adopt come originally from the study of Yang et al (2010).…”

Section: Radiative Transfer Simulationsmentioning

confidence: 99%

Using CO line ratios to trace the physical properties of molecular clouds

Peñaloza

Clark

Glover

et al. 2016

Mon. Not. R. Astron. Soc.

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The carbon monoxide (CO) rotational transition lines are the most common tracers of molecular gas within giant molecular clouds (MCs). We study the ratio (R 2−1/1−0 ) between CO's first two emission lines and examine what information it provides about the physical properties of the cloud. To study R 2−1/1−0 we perform smooth particle hydrodynamic simulations with time dependent chemistry (using GADGET-2), along with post-process radiative transfer calculations on an adaptive grid (using RADMC-3D) to create synthetic emission maps of a MC. R 2−1/1−0 has a bimodal distribution that is a consequence of the excitation properties of each line, given that J = 1 reaches local thermal equilibrium (LTE) while J = 2 is still sub-thermally excited in the considered clouds. The bimodality of R 2−1/1−0 serves as a tracer of the physical properties of different regions of the cloud and it helps constrain local temperatures, densities and opacities. Additionally this bimodal structure shows an important portion of the CO emission comes from diffuse regions of the cloud, suggesting that the commonly used conversion factor of R 2−1/1−0 ∼ 0.7 between both lines may need to be studied further.

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An atomic and molecular database for analysis of submillimetre line observations

Cited by 1,420 publications

References 106 publications

DIGIT survey of far-infrared lines from protoplanetary disks

DIGIT survey of far-infrared lines from protoplanetary disks

A self-consistent model for the evolution of the gas produced in the debris disc of β Pictoris

Using CO line ratios to trace the physical properties of molecular clouds

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