Carina Arasa (1,2), Jesper Koning (1), Geert-Jan Kroes (1), Catherine Walsh (2), Ewine F. van Dishoeck (2,3) ((1) Gorlaeus Laboratories, Leiden Institute of Chemistry, Leiden University, P. O. Box 9502, 2300 RA Leiden, The Netherlands, (2) Leiden Observatory, Leiden University, P. O. Box 9513, 2300 RA Leiden, The Netherlands, (3) Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748 Garching, Germany)
(Submitted on 2 Mar 2015)
The HDO/H2O ratio in interstellar gas is often used to draw conclusions on the origin of water in star-forming regions and on Earth. In cold cores and in the outer regions of protoplanetary disks, gas-phase water comes from photodesorption of water ice. We present fitting formulae for implementation in astrochemical models using photodesorption efficiencies for all water ice isotopologues obtained using classical molecular dynamics simulations. We investigate if the gas-phase HDO/H2O ratio reflects that present in the ice or whether fractionation can occur during photodesorption. Probabilities for the top four monolayers are presented for photodesorption of X (X=H,D) atoms, OX radicals, and X2O and HDO molecules following photodissociation of H2O, D2O, and HDO in H2O amorphous ice at temperatures from 10-100 K. Isotope effects are found for all products: (1) H atom photodesorption probabilities from H2O ice are larger than those for D atom photodesorption from D2O ice by a factor of 1.1; the ratio of H and D photodesorbed upon HDO photodissociation is a factor of 2. This process will enrich the ice in deuterium atoms over time; (2) the OD/OH photodesorption ratio upon D2O and H2O photodissociation is on average a factor of 2, but the ratio upon HDO photodissociation is almost constant at unity for all temperatures; (3) D atoms are more effective in kicking out neighbouring water molecules than H atoms. However, the ratio of the photodesorbed HDO and H2O molecules is equal to the HDO/H2O ratio in the ice, therefore, there is no isotope fractionation upon HDO and H2O photodesorption. Nevertheless, the enrichment of the ice in D atoms due to photodesorption can over time lead to an enhanced HDO/H2O ratio in the ice, and, when photodesorbed, also in the gas. The extent to which the ortho/para ratio of H2O can be modified by the photodesorption process is also discussed. (Abridged)
Comments: 12 pages, 3 figures, accepted for publication in Astronomy & Astrophysics
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1503.00394 [astro-ph.GA](or arXiv:1503.00394v1 [astro-ph.GA] for this version)
Submission history
From: Catherine Walsh
[v1] Mon, 2 Mar 2015 02:19:34 GMT (202kb,D)
http://arxiv.org/abs/1503.00394
Read the original post:
Photodesorption of H2O, HDO, and D2O ice and its impact on fractionation
- Rotational spectra of isotopic species of methyl cyanide, CH_3CN, in their ground vibrational states up to terahertz frequencies - November 8th, 2009 [November 8th, 2009]
- Cosmological parameter extraction and biases from type Ia supernova magnitude evolution - November 8th, 2009 [November 8th, 2009]
- Continuous monitoring of pulse period variations in Hercules X-1 using Swift/BAT - November 8th, 2009 [November 8th, 2009]
- Constraining the ortho-to-para ratio of H{_2} with anomalous H{_2}CO absorption - November 8th, 2009 [November 8th, 2009]
- A photometric and spectroscopic study of the new dwarf spheroidal galaxy in Hercules - Metallicity, velocities, and a clean list of RGB members - November 8th, 2009 [November 8th, 2009]
- Luminosities and mass-loss rates of SMC and LMC AGB stars and red supergiants - November 8th, 2009 [November 8th, 2009]
- Electron beam – plasma system with the return current and directivity of its X-ray emission - November 8th, 2009 [November 8th, 2009]
- The propagation of the shock wave from a strong explosion in a plane-parallel stratified medium: the Kompaneets approximation - November 8th, 2009 [November 8th, 2009]
- Analysis of hydrogen-rich magnetic white dwarfs detected in the Sloan Digital Sky Survey - November 8th, 2009 [November 8th, 2009]
- Letter: Centaurus A as TeV \gamma-ray and possible UHE cosmic-ray source - November 8th, 2009 [November 8th, 2009]
- Young pre-low-mass X-ray binaries in the propeller phase - Nature of the 6.7-h periodic X-ray source 1E 161348-5055 in RCW 103 - November 8th, 2009 [November 8th, 2009]
- Radiative rates and electron impact excitation rates for transitions in Cr VIII - November 8th, 2009 [November 8th, 2009]
- Solar granulation from photosphere to low chromosphere observed in Ba II 4554 Å line - November 8th, 2009 [November 8th, 2009]
- Does the HD 209458 planetary system pose a challenge to the stellar atmosphere models? - November 8th, 2009 [November 8th, 2009]
- Effect of asymmetry of the radio source distribution on the apparent proper motion kinematic analysis - November 8th, 2009 [November 8th, 2009]
- Destriping CMB temperature and polarization maps - November 8th, 2009 [November 8th, 2009]
- Search for cold debris disks around M-dwarfs. II - November 8th, 2009 [November 8th, 2009]
- Precise data on Leonid fireballs from all-sky photographic records - November 8th, 2009 [November 8th, 2009]
- An X-ray view of 82 LINERs with Chandra and XMM-Newton data - November 8th, 2009 [November 8th, 2009]
- Radio observations of ZwCl 2341.1+0000: a double radio relic cluster - November 8th, 2009 [November 8th, 2009]
- Candidate free-floating super-Jupiters in the young \sigma Orionis open cluster - November 8th, 2009 [November 8th, 2009]
- The metallicity gradient as a tracer of history and structure: the Magellanic Clouds and M33 galaxies - November 8th, 2009 [November 8th, 2009]
- XMMSL1 J060636.2-694933: an XMM-Newton slew discovery and Swift/Magellan follow up of a new classical nova in the LMC - November 8th, 2009 [November 8th, 2009]
- The inner rim structures of protoplanetary discs - November 8th, 2009 [November 8th, 2009]
- The solar Ba{\sf II} 4554 Å line as a Doppler diagnostic: NLTE analysis in 3D hydrodynamical model - November 8th, 2009 [November 8th, 2009]
- Magnetic evolution of superactive regions - Complexity and potentially unstable magnetic discontinuities - November 8th, 2009 [November 8th, 2009]
- Low-mass protostars and dense cores in different evolutionary stages in IRAS 00213+6530 - November 8th, 2009 [November 8th, 2009]
- PMAS optical integral field spectroscopy of luminous infrared galaxies - I. The atlas - November 8th, 2009 [November 8th, 2009]
- First AGILE catalog of high-confidence gamma-ray sources - November 8th, 2009 [November 8th, 2009]
- Radiative hydrodynamics simulations of red supergiant stars - I. interpretation of interferometric observations - November 8th, 2009 [November 8th, 2009]
- Extrasolar planets and brown dwarfs around A–F type stars - VII. \theta Cygni radial velocity variations: planets or stellar phenomenon? - November 8th, 2009 [November 8th, 2009]
- Cosmic rays and the magnetic field in the nearby starburst galaxy NGC 253 - II. The magnetic field structure - November 8th, 2009 [November 8th, 2009]
- Physical structure and water line spectrum predictions of the intermediate mass protostar OMC2-FIR4 - November 8th, 2009 [November 8th, 2009]
- The bright galaxy population of five medium redshift clusters - II. Quantitative galaxy morphology - November 8th, 2009 [November 8th, 2009]
- Dust in brown dwarfs and extra-solar planets - II. Cloud formation for cosmologically evolving abundances - November 8th, 2009 [November 8th, 2009]
- The quiet Sun magnetic field observed with ZIMPOL on THEMIS - I. The probability density function - November 8th, 2009 [November 8th, 2009]
- Complexity in the sunspot cycle - November 8th, 2009 [November 8th, 2009]
- Properties and nature of Be stars - 26. Long-term and orbital changes of \zeta Tauri - November 8th, 2009 [November 8th, 2009]
- The massive Wolf-Rayet binary LSS 1964 (=WR 29) - II. The V light curve - November 8th, 2009 [November 8th, 2009]
- Supernova progenitor stars in the initial range of 23 to 33 solar masses and their relation with the SNR Cassiopeia A - November 8th, 2009 [November 8th, 2009]
- The Hertzsprung-Russell Diagram of Star Clusters - November 8th, 2009 [November 8th, 2009]
- Table of the 10 Brightest stars within 10 Parsecs of the Sun - November 8th, 2009 [November 8th, 2009]
- The Hertzsprung-Russell Diagram of the Nearest Stars - November 8th, 2009 [November 8th, 2009]
- Magnitude and Color in Astronomy - November 8th, 2009 [November 8th, 2009]
- Stellar Types - November 8th, 2009 [November 8th, 2009]
- Brown Dwarfs - November 8th, 2009 [November 8th, 2009]
- Spotting the Minimum - November 8th, 2009 [November 8th, 2009]
- The Structure and Evolution of Brown Dwarfs - November 8th, 2009 [November 8th, 2009]
- No Bang from the Big Bang Machine - November 8th, 2009 [November 8th, 2009]
- The Sizes of the Stars and the Planets - November 8th, 2009 [November 8th, 2009]
- An Implausible Light Thrust - November 8th, 2009 [November 8th, 2009]
- the Masses of Degenerate Objects - November 8th, 2009 [November 8th, 2009]
- Degeneracy Pressure - November 8th, 2009 [November 8th, 2009]
- Introduction to Degenerate Objects - November 8th, 2009 [November 8th, 2009]
- The Radii of Degenerate Objects - November 8th, 2009 [November 8th, 2009]
- The Inevitability of Black Holes - November 8th, 2009 [November 8th, 2009]
- Scientific Pig-Out - November 8th, 2009 [November 8th, 2009]
- The Neutrino Cooling of Degenerate Dwarfs - November 8th, 2009 [November 8th, 2009]
- The Neutrino Cooling of Neutron Stars - November 8th, 2009 [November 8th, 2009]
- Overview of Supernovae - November 8th, 2009 [November 8th, 2009]
- Energetics of Thermonuclear Supernovae - November 8th, 2009 [November 8th, 2009]
- Thermonuclear Supernovae - November 8th, 2009 [November 8th, 2009]
- Nuclear Reactions in Thermonuclear Supernovae - November 8th, 2009 [November 8th, 2009]
- Core-Collapse Supernovae - November 8th, 2009 [November 8th, 2009]
- Neutrinos and SN 1987A - November 8th, 2009 [November 8th, 2009]
- Revealing the sub-AU asymmetries of the inner dust rim in the disk around the Herbig Ae star R Coronae Austrinae - December 13th, 2009 [December 13th, 2009]
- Probing the dust properties of galaxies up to submillimetre wavelengths - I. The spectral energy distribution of dwarf galaxies using LABOCA - December 13th, 2009 [December 13th, 2009]
- On the physical origin of the second solar spectrum of the Sc II line at 4247 Å - December 13th, 2009 [December 13th, 2009]
- On detecting the large separation in the autocorrelation of stellar oscillation times series - December 13th, 2009 [December 13th, 2009]
- Imaging the spotty surface of Betelgeuse in the H band - December 13th, 2009 [December 13th, 2009]
- Chandra observation of Cepheus A: the diffuse emission of HH 168 resolved - December 13th, 2009 [December 13th, 2009]
- A planetary eclipse map of CoRoT-2a - Comprehensive lightcurve modeling combining rotational-modulation and transits - December 13th, 2009 [December 13th, 2009]
- The chemical composition of carbon stars. The R-type stars - December 13th, 2009 [December 13th, 2009]
- Flow instabilities of magnetic flux tubes - IV. Flux storage in the solar overshoot region - December 13th, 2009 [December 13th, 2009]
- Fragmentation of a dynamically condensing radiative layer - December 13th, 2009 [December 13th, 2009]
- Temporal variations of the CaXIX spectra in solar flares - December 13th, 2009 [December 13th, 2009]
- Deuterium chemistry in the Orion Bar PDR - “Warm” chemistry starring CH_{2}D^+ - December 13th, 2009 [December 13th, 2009]
- Metal abundances in the cool cores of galaxy clusters - December 13th, 2009 [December 13th, 2009]
- The nature of the X-ray binary IGR J19294+1816 from INTEGRAL, RXTE, and Swift observations - December 13th, 2009 [December 13th, 2009]
- Relating basic properties of bright early-type dwarf galaxies to their location in Abell 901/902 - December 13th, 2009 [December 13th, 2009]