Observations and modelling of CO and [C i] in protoplanetary disks

Kama, M.; Bruderer, S.; Carney, M. T.; Hogerheijde, M. R.; Dishoeck, E. F. van; Fedele, D.; Baryshev, A.; Boland, W.; Güsten, R.; Aikutalp, A.; Choi, Yoon Kyung; Endo, Akira; Frieswijk, W.; Karska, A.; Klaassen, Pamela; Koumpia, E.; Kristensen, L. E.; Leurini, S.; Nagy, Z.; Beaupuits, J.-P. Perez; Risacher, C.; Marel, Nienke van der; Kempen, T. A. van; Weeren, R. J. van; Wyrowski, F.; Yıldız, U. A.

doi:10.1051/0004-6361/201526791

Cited by 86 publications

(119 citation statements)

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“…The line was detected previously towards DM Tau by Tsukagoshi et al (2015) and Kama et al (2016), however it is single-peaked and narrower than the double-peaked CO profiles seen from that source, which suggests contamination by a compact residual envelope and requires further follow-up. Our new data, listed in Table 1, were supplemented with continuum and spectral line data from the literature, listed in Appendix C.…”

Section: Overview Of the Spectramentioning

confidence: 57%

“…The [C i] detections shown in Fig. 1 and the CO 6-5 detections were presented, but not analyzed in detail, as part of a large survey in Kama et al (2016).…”

Section: Observationsmentioning

confidence: 99%

“…Kama et al (2016). The two main sources of uncertainty are the radial extent of the gas disk and the gas to dust ratio.…”

Section: Bergin Et Al 2013) the Spectral Line Profiles Of Co And [C I]mentioning

confidence: 99%

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Volatile-carbon locking and release in protoplanetary disks

Kama

Bruderer

Dishoeck

et al. 2016

A&A

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203

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Aims. The composition of planetary solids and gases is largely rooted in the processing of volatile elements in protoplanetary disks. To shed light on the key processes, we carry out a comparative analysis of the gas-phase carbon abundance in two systems with a similar age and disk mass, but different central stars: HD 100546 and TW Hya. Methods. We combine our recent detections of C 0 in these disks with observations of other carbon reservoirs (CO, C + , C 2 H) and gas-mass and warm-gas tracers (HD, O 0 ), as well as spatially resolved ALMA observations and the spectral energy distribution. The disks are modelled with the DALI 2D physical-chemical code. Stellar abundances for HD 100546 are derived from archival spectra. Results. Upper limits on HD emission from HD 100546 place an upper limit on the total disk mass of ≤0.1 M . The gas-phase carbon abundance in the atmosphere of this warm Herbig disk is, at most, moderately depleted compared to the interstellar medium, with [C]/[H] gas = (0.1−1.5) × 10 −4 . HD 100546 itself is a λ Boötis star, with solar abundances of C and O but a strong depletion of rockforming elements. In the gas of the T Tauri disk TW Hya, both C and O are strongly underabundant, with [C]/[H] gas = (0.2−5.0)×10 −6 and C/O > 1. We discuss evidence that the gas-phase C and O abundances are high in the warm inner regions of both disks. Our analytical model, including vertical mixing and a grain size distribution, reproduces the observed [C]/[H] gas in the outer disk of TW Hya and allows to make predictions for other systems.

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Section: Overview Of the Spectramentioning

confidence: 57%

“…The [C i] detections shown in Fig. 1 and the CO 6-5 detections were presented, but not analyzed in detail, as part of a large survey in Kama et al (2016).…”

Section: Observationsmentioning

confidence: 99%

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Volatile-carbon locking and release in protoplanetary disks

Kama

Bruderer

Dishoeck

et al. 2016

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“…It closely resembles a 4000 K blackbody with a 10000 K blackbody component to represent the observed UV excess (following the prescription in Kama et al 2016a, see also Figure 3 and Table 3 in Kama et al 2016b).…”

Section: Grid Of Modelsmentioning

confidence: 73%

Far-infrared HD emission as a measure of protoplanetary disk mass

Trapman

Miotello

Kama

et al. 2017

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Context. Protoplanetary disks around young stars are the sites of planet formation. While the dust mass can be estimated using standard methods, determining the gas mass -and thus the amount of material available to form giant planets -has proven to be very difficult. Hydrogen deuteride (HD) is a promising alternative to the commonly-used gas mass tracer, carbon monoxide. However, its potential has not yet been investigated with models incorporating both HD and CO isotopologue-specific chemistry, and its sensitivity to uncertainties in disk parameters has not yet been quantified. Aims. To examine the robustness of HD as tracer of the disk gas mass, specifically the effect of gas mass on the HD far infrared emission and its sensitivity to the vertical structure. Also, to provide requirements for future far-infrared missions such as SPICA. Methods. Deuterium chemistry reactions relevant for HD were implemented in the thermochemical code DALI and more than 160 disk models were run for a range of disk masses and vertical structures. Results. The HD J=1-0 line intensity depends directly on the gas mass through a sublinear power law relation with a slope of ∼0.8. Assuming no prior knowledge about the vertical structure of a disk and using only the HD 1-0 flux, gas masses can be estimated to within a factor of two for low mass disks (M disk ≤ 10 −3 M ). For more massive disks, this uncertainty increases to more than an order of magnitude. Adding the HD 2-1 line or independent information about the vertical structure can reduce this uncertainty to a factor of ∼ 3 for all disk masses. For TW Hya, using the radial and vertical structure from Kama et al. (2016b) the observations constrain the gas mass to 6 · 10 −3 M ≤ M disk ≤ 9 · 10 −3 M . Future observations require a 5σ sensitivity of 1.8 · 10 −20 W m −2 (2.5 · 10 −20 W m −2 ) and a spectral resolving power R ≥ 300 (1000) to detect HD 1-0 (HD 2-1) for all disk masses above 10 −5 M with a line-to-continuum ratio ≥ 0.01. Conclusions. These results show that HD can be used as an independent gas mass tracer with a relatively low uncertainty and should be considered as an important science goal for future far-infrared missions.

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“…There is observational evidence for CO depletion in protoplanetary disks (Dutrey et al 1997;Bruderer et al 2012;Favre et al 2013;Kama et al 2016a;Schwarz et al 2016;McClure et al 2016). The best constraint case is TW Hya.…”

Section: Co Depletionmentioning

confidence: 99%

Stellar energetic particle ionization in protoplanetary disks around T Tauri stars

Rab

Güdel

Padovani

et al. 2017

A&A

102

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Context. Anomalies in the abundance measurements of short lived radionuclides in meteorites indicate that the protosolar nebulae was irradiated by a high amount of energetic particles (E 10 MeV). The particle flux of the contemporary Sun cannot explain these anomalies. However, similar to T Tauri stars the young Sun was more active and probably produced enough high energy particles to explain those anomalies. Aims. We want to study the interaction of stellar energetic particles with the gas component of the disk (i.e. ionization of molecular hydrogen) and identify possible observational tracers of this interaction. Methods. We use a 2D radiation thermo-chemical protoplanetary disk code to model a disk representative for T Tauri stars. We use a particle energy distribution derived from solar flare observations and an enhanced stellar particle flux proposed for T Tauri stars. For this particle spectrum we calculate the stellar particle ionization rate throughout the disk with an accurate particle transport model. We study the impact of stellar particles for models with varying X-ray and cosmic-ray ionization rates. Results. We find that stellar particle ionization has a significant impact on the abundances of the common disk ionization tracers HCO + and N 2 H + , especially in models with low cosmic-ray ionization rates (e.g. 10 −19 s −1 for molecular hydrogen). In contrast to cosmic rays and X-rays, stellar particles cannot reach the midplane of the disk. Therefore molecular ions residing in the disk surface layers are more affected by stellar particle ionization than molecular ions tracing the cold layers/midplane of the disk. Conclusions. Spatially resolved observations of molecular ions tracing different vertical layers of the disk allow to disentangle the contribution of stellar particle ionization from other competing ionization sources. Modeling such observations with a model like the one presented here allows to constrain the stellar particle flux in disks around T Tauri stars.

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Observations and modelling of CO and [C i] in protoplanetary disks

Cited by 86 publications

References 103 publications

Volatile-carbon locking and release in protoplanetary disks

Volatile-carbon locking and release in protoplanetary disks

Far-infrared HD emission as a measure of protoplanetary disk mass

Stellar energetic particle ionization in protoplanetary disks around T Tauri stars

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