Multiple Paths of Deuterium Fractionation in Protoplanetary Disks

  title={Multiple Paths of Deuterium Fractionation in Protoplanetary Disks},
  author={Yuri Aikawa and Kenji Furuya and Ugo Hincelin and Eric Herbst},
  journal={Japan Geoscience Union},
We investigate deuterium chemistry coupled with the nuclear spin-state chemistry of H$_2$ and H$_3^+$ in protoplanetary disks. Multiple paths of deuterium fractionation are found; exchange reactions with D atoms, such as HCO$^+$ + D, are effective in addition to those with HD. In a disk model with grain sizes appropriate for dark clouds, the freeze-out of molecules is severe in the outer midplane, while the disk surface is shielded from UV radiation. Gaseous molecules, including DCO$^+$, thus… 
The Effect of Carbon Grain Destruction on the Chemical Structure of Protoplanetary Disks
The bulk composition of the Earth is dramatically carbon poor compared to that of the interstellar medium, and this phenomenon extends to the asteroid belt. To interpret this carbon deficit problem,
Molecules with ALMA at Planet-forming Scales (MAPS). I. Program Overview and Highlights
Planets form and obtain their compositions in dust- and gas-rich disks around young stars, and the outcome of this process is intimately linked to the disk chemical properties. The distributions of
Molecules with ALMA at Planet-forming Scales (MAPS). XIII. HCO+ and Disk Ionization Structure
We observed HCO+ J = 1 − 0 and H13CO+ J = 1 − 0 emission toward the five protoplanetary disks around IM Lup, GM Aur, AS 209, HD 163296, and MWC 480 as part of the MAPS project. HCO+ is detected and
Molecules with ALMA at Planet-forming Scales (MAPS). X. Studying Deuteration at High Angular Resolution toward Protoplanetary Disks
Deuterium fractionation is dependent on various physical and chemical parameters. Thus, the formation location and thermal history of material in the solar system is often studied by measuring its
Gas Density Perturbations Induced by One or More Forming Planets in the AS 209 Protoplanetary Disk as Seen with ALMA
The formation of planets occurs within protoplanetary disks surrounding young stars, resulting in perturbation of the gas and dust surface densities. Here we report the first evidence of spatially
Temperature Spectra of Interstellar Dust Grains Heated by Cosmic Rays. II. Dark Cloud Cores
  • J. Kalvāns
  • Physics
    The Astrophysical Journal Supplement Series
  • 2018
Cosmic-ray (CR) induced heating of whole interstellar grains is an important desorption mechanism for grain surface molecules in interstellar molecular clouds. This study aims to provide a detailed
Revealing the chemical structure of the Class I disc Oph-IRS 67
Context. Recent results suggest that the first steps towards planet formation may be already taking place in protoplanetary discs during the first 100 000 yr after stars form. It is therefore crucial
Volatile Species in Comet 67P/Churyumov-Gerasimenko: Investigating the Link from the ISM to the Terrestrial Planets
Comets contain abundant amounts of organic and inorganic species. Many of the volatile molecules in comets have also been observed in the interstellar medium and some of them even with similar
Detection of H2 in the TWA 7 System: A Probable Circumstellar Origin
Using HST–COS far-UV spectra, we have discovered warm molecular hydrogen in the TWA 7 system. TWA 7, a ∼9 Myr old M2.5 star, has a cold debris disk and has previously shown no signs of accretion.
D/H in the refractory organics of comet 67P/Churyumov-Gerasimenko measured by Rosetta/COSIMA
The D/H ratio is a clue to the origin and evolution of hydrogen-bearing chemical species in Solar system materials. D/H has been observed in the coma of many comets, but most such measurements have


Deuterium Fractionation in Protoplanetary Disks
We investigate the chemistry of deuterium-bearing molecules in outer regions of protoplanetary disks, where comets may form. We find that molecules formed in the disk have higher D/H ratios (by which
The chemistry of multiply deuterated molecules in protoplanetary disks : I. the outer disk
We present new models of the deuterium chemistry in protoplanetary disks, including, for the first time, multiply deuterated species. We use these models to explore whether observations in
We investigate water and deuterated water chemistry in turbulent protoplanetary disks. Chemical rate equations are solved with the diffusion term, mimicking turbulent mixing in a vertical direction.
Evidence for Multiple Pathways to Deuterium Enhancements in Protoplanetary Disks
The distributions of deuterated molecules in protoplanetary disks are expected to depend on the molecular formation pathways. We use observations of spatially resolved DCN emission from the disk
Evidence for DCO+ as a probe of ionization in the warm disk surface
In this Letter we model the chemistry of DCO$^{+}$ in protoplanetary disks. We find that the overall distribution of the DCO$^{+}$ abundance is qualitatively similar to that of CO but is dominated by
Reprocessing of Ices in Turbulent Protoplanetary Disks: Carbon and Nitrogen Chemistry
We study the influence of the turbulent transport on ice chemistry in protoplanetary disks, focusing on carbon and nitrogen bearing molecules. Chemical rate equations are solved with the diffusion
Evolution of Molecular Abundances in Proto-planetary Disks with Accretion Flow
We investigate the evolution of molecular abundances in a protoplanetary disk in which matter is accreting toward the central star by solving numerically the reaction equations of molecules as an
Volatile carbon locking and release in protoplanetary disks. A study of TW Hya and HD 100546
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
Exclusion of Cosmic Rays in Protoplanetary Disks. II. Chemical Gradients and Observational Signatures
The chemical properties of protoplanetary disks are especially sensitive to their ionization environment. Sources of molecular gas ionization include cosmic rays, stellar X-rays and short-lived