The chemical history of molecules in circumstellar disks. I. Ices

Abstract

(Abridged) Aims & Methods. A two-dimensional, semi-analytical model is presented that follows, for the first time, the chemical evolution from a collapsing molecular cloud (a pre-stellar core) to a protostar and circumstellar disk. The model computes infall trajectories from any point in the cloud and tracks the radial and vertical motion of material in the viscously evolving disk. It includes a full time-dependent radiative transfer treatment of the dust temperature, which controls much of the chemistry. A small parameter grid is explored to understand the effects of the sound speed and the mass and rotation of the cloud. The freeze-out and evaporation of carbon monoxide (CO) and water (H2O), as well as the potential for forming complex organic molecules in ices, are considered as important first steps to illustrate the full chemistry. Results. Both species freeze out towards the centre before the collapse begins. Pure CO ice evaporates during the infall phase and re-adsorbs in those parts of the disk that cool below the CO desorption temperature of ~18 K. H2O remains solid almost everywhere during the infall and disk formation phases and evaporates within ~10 AU of the star. Mixed CO-H2O ices are important in keeping some solid CO above 18 K and in explaining the presence of CO in comets. Material that ends up in the planet- and comet-forming zones of the disk is predicted to spend enough time in a warm zone during the collapse to form first-generation complex organic species on the grains. The dynamical timescales in the hot inner envelope (hot core or hot corino) are too short for abundant formation of second-generation molecules by high-temperature gas-phase chemistry.

18 pages, 16 figures, accepted by A&A

References in corpus (12)

• Cold Dark Clouds: The Initial Conditions for Star Formation
• Complex Chemistry in Star-Forming Regions: An Expanded Gas-Grain Warm-up Chemical Model
• Formation of methyl formate and other organic species in the warm-up phase of hot molecular cores
• A Submillimeter View of Circumstellar Dust Disks in $\rho$ Ophiuchus
• The Mass Distribution and Lifetime of Prestellar Cores in Perseus, Serpens, and Ophiuchus
• The Evolution of Outflow-Envelope Interactions in Low-Mass Protostars
• Molecular Evolution and Star Formation: From Prestellar Cores to Protostellar Cores
• On the Location of the Snow Line in a Protoplanetary Disk
• Why Do T Tauri Disks Accrete?
• Gas-phase CO in protoplanetary disks: a challenge for turbulent mixing
• Crystalline silicates as a probe of disk formation history
• Time-dependent CO depletion during the formation of protoplanetary disks

Cited by in corpus (36)

• Gas- and dust evolution in protoplanetary disks
• Photochemistry and astrochemistry: photochemical pathways to interstellar complex organic molecules
• The ancient heritage of water ice in the solar system
• Complex organic molecules in protoplanetary disks
• Setting the volatile composition of (exo)planet-building material. Does chemical evolution in disk midplanes matter?
• Different dust and gas radial extents in protoplanetary disks: consistent models of grain growth and CO emission
• ALMA Observations of Infalling Flows toward the Keplerian Disk around the Class I Protostar L1489 IRS
• Disk evolution, element abundances and cloud properties of young gas giant planets
• An ALMA survey of DCN/H${}^{13}$CN and DCO${}^{+}$/H${}^{13}$CO${}^{+}$ in protoplanetary disks
• Cometary ices in forming protoplanetary disc midplanes
• CO2 formation in quiescent clouds; an experimental study of the CO + OH pathway
• Molecule sublimation as a tracer of protostellar accretion: Evidence for accretion bursts from high angular resolution C18O images
• Methanol Along the Path from Envelope to Protoplanetary Disc
• From stellar nebula to planetesimals
• A primordial origin for molecular oxygen in comets: A chemical kinetics study of the formation and survival of O${}_2$ ice from clouds to disks
• The Role of Ice Compositions for Snowlines and the C/N/O Ratios in Active Disks
• Complex Organic Molecules Towards Embedded Low-Mass Protostars
• Water delivery from cores to disks: deuteration as a probe of the prestellar inheritance of H2O
• Triggered Star Formation Inside the Shell of a Wolf-Rayet Bubble as the origin of the Solar System
• The composition of the protosolar disk and the formation conditions for comets
• The chemistry of episodic accretion in embedded objects. 2D radiation thermo-chemical models of the post-burst phase
• Decrease of the organic deuteration during the evolution of Sun-like protostars: the case of SVS13-A
• High D${}_2$O/HDO ratio in the inner regions of the low-mass protostar NGC1333 IRAS2A
• Detections of trans-Neptunian ice in protoplanetary disks
• A low-mass protostar's disk-envelope interface: disk-shadowing evidence from ALMA DCO+ observations of VLA1623
• Photodesorption of H2O, HDO, and D2O ice and its impact on fractionation
• Micrometer-Sized Water Ice Particles for Planetary Science Experiments: Influence of Surface Structure on Collisional Properties
• Evaporation of grain-surface species by shock waves in proto-planetary disk
• 1000 AU Exterior Arcs Connected to the Protoplanetary Disk around HL Tau
• Complex organic molecules along the accretion flow in isolated and externally irradiated protoplanetary disks
• Formation of freely floating sub-stellar objects via close encounters
• Chemistry in a forming protoplanetary disk: main accretion phase
• Testing protostellar disk formation models with ALMA observations
• Environment and Protostellar Evolution
• Astro & cosmo-chemical consequences of accretion bursts I: the D/H ratio of water
• Computational modeling of the class I low-mass protostar Elias 29 applying optical constants of ices processed by high energy cosmic ray analogs