Chemistry in disks. IX. Observations and modelling of HCO+ and DCO+ in DM Tauri
Richard Teague,D. A. Semenov,Stephane Guilloteau,Th. Henning,Anne Dutrey,Valentine Wakelam,E. Chapillon,Vincent Piétu +7 more
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In this paper, the deuteration and ionization structure of the DM Tau disk via interferometric observations and modelling of the key molecular ions, HCO+ and DCO+ was studied.Abstract:
Aims. We study the deuteration and ionization structure of the DM Tau disk via interferometric observations and modelling of the key molecular ions, HCO+ and DCO+ .Methods. The Plateau de Bure Array is used to observe DM Tau in lines of HCO+ (1−0), (3−2) and DCO+ (3−2) with a ~ 1.5′′ angular and ~0.2 km s-1 spectral resolution. Using a power-law fitting approach the observed column densities profiles are derived and thus the isotopic ratio R D = DCO+ /HCO+ . Chemical modelling allowed an exploration of the sensitivity of HCO+ and DCO+ abundances to physical parameters out with temperature. A steady state approximation was employed to observationally constrain the ionization fraction x (e− ).Results. Fitting of radiative transfer models suggests that there is a chemical hole in HCO+ and DCO+ , extending up to 50 AU from the star. More work is required to discern the cause of this. The observed column densities of HCO+ and DCO+ at 100 AU were (9.8+0.3 -0.7 ) × 1012 and (1.2 ± 0.7) × 1012 cm-2 respectively. Where both HCO+ and DCO+ were present, R D was found to increase radially from 0.1 at 50 AU to 0.2 at 450 AU. This behaviour was well reproduced by the chemical model. The X-ray luminosity of the central star, the interstellar UV and CO depletion were found to be the most important physical parameters controlling the abundances of HCO+ and DCO+ . Differences in the vertical extent of HCO+ and DCO+ molecular layers resulted in different responses to changing physical parameters, manifesting as radial gradients in R D . The ionization fraction was found to be x (e− ) ~ 10-7 in the molecular layer, comparable to the disk averaged value. Modelling shows that while HCO+ is the most dominant charged molecular ion in our disk model, atomic ions, such as C+ , S+ , H+ , Na+ and Mg+ , dominate the charge in both the molecular layer and disk atmosphere.Conclusions. A high value of R D is indicative of continued deuterium fractionation in a protoplanetary disk after pre/protostellar phases. Radial properties of R D can be employed to discern the importance of ionization from X-rays and UV, thus necessitating the need for more, high resolution observations of DCO+ and other deuterated species in disks. A steady-state approach commonly adopted for constraining ionization degree in prestellar cores is not applicable for disks where accurate determination of the ionization fraction in the molecular layer requires knowledge of the atomic ions present as molecular ions are relatively sparse.read more
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The Disk Substructures at High Angular Resolution Project (DSHARP). II. Characteristics of Annular Substructures
Jane Huang,Sean M. Andrews,Cornelis P. Dullemond,Andrea Isella,Laura M. Pérez,Viviana V. Guzmán,Karin I. Öberg,Zhaohuan Zhu,Shangjia Zhang,Xue-Ning Bai,Myriam Benisty,Myriam Benisty,Tilman Birnstiel,John M. Carpenter,A. Meredith Hughes,Luca Ricci,E. Weaver,David J. Wilner +17 more
TL;DR: In this article, the authors present a systematic analysis of annular substructures in the 18 single-disk systems targeted in this survey, and find that annular structures can occur at virtually any radius where millimeter continuum emission is detected and range in widths from a few astronomical units to tens of astronomical units.
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The comet-like composition of a protoplanetary disk as revealed by complex cyanides
Karin I. Öberg,Viviana V. Guzmán,Kenji Furuya,Chunhua Qi,Yuri Aikawa,Sean M. Andrews,Ryan A. Loomis,David J. Wilner +7 more
TL;DR: It is found that the abundance ratios of these nitrogen-bearing organics in the gas phase are similar to those in comets, which implies that complex organics accompany simpler volatiles in protoplanetary disks, and that the rich organic chemistry of the authors' solar nebula was not unique.
Journal ArticleDOI
A Three-dimensional View of Turbulence: Constraints on Turbulent Motions in the HD 163296 Protoplanetary Disk Using DCO+
Kevin Flaherty,A. Meredith Hughes,Sanaea C. Rose,Jacob B. Simon,Jacob B. Simon,Chunhua Qi,Sean M. Andrews,Ágnes Kóspál,Ágnes Kóspál,David J. Wilner,Eugene Chiang,Philip J. Armitage,Xue-Ning Bai +12 more
TL;DR: In this paper, the authors present ALMA observations of three molecules (DCO$^+$(3-2), C$^{18}$O(2-1) and CO(2)-1) from the disk around HD 163296.
Journal ArticleDOI
Grain Surface Models and Data for Astrochemistry
Herma M. Cuppen,Catherine Walsh,Catherine Walsh,Thanja Lamberts,Thanja Lamberts,D. Semenov,Robin T. Garrod,E. M. Penteado,Sergio Ioppolo +8 more
TL;DR: A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes.
Journal ArticleDOI
Three Radial Gaps in the Disk of TW Hydrae Imaged with SPHERE
R. van Boekel,Th. Henning,J. Menu,J. Menu,J. de Boer,J. de Boer,Maud Langlois,Maud Langlois,André Müller,André Müller,Henning Avenhaus,Anthony Boccaletti,H. M. Schmid,C. Thalmann,Myriam Benisty,Myriam Benisty,Carsten Dominik,Ch. Ginski,Julien Girard,Julien Girard,Julien Girard,D. Gisler,D. Gisler,A. Lobo Gomes,Francois Menard,Francois Menard,Michiel Min,Michiel Min,A. Pavlov,Adriana Pohl,Sascha P. Quanz,P. Rabou,P. Rabou,Ronald Roelfsema,Jean-François Sauvage,Richard Teague,Francois Wildi,Alice Zurlo,Alice Zurlo,Alice Zurlo +39 more
TL;DR: In this article, scattered light images of the TW Hya disk performed with the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument in Polarimetric Differential Imaging mode at 0.63, 0.79, 1.24, and 1.62 mu m were presented.
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