2007A&A...463..369T


C.D.S. - SIMBAD4 rel 1.7 - 2019.08.22CEST23:11:12

2007A&A...463..369T - Astronomy and Astrophysics, volume 463, 369-392 (2007/2-3)

2-D preplanetary accretion disks. I. Hydrodynamics, chemistry, and mixing processes.

TSCHARNUTER W.M. and GAIL H.-P.

Abstract (from CDS):

We outline a numerical method to calculate spatially two-dimensional (2-D) reactive flows and mixing processes in preplanetary accretion disks and present first results. The numerical efficiency and robustness is demonstrated by following the hydrodynamical and chemical evolution of the disk from a highly non-stationary dynamical ``switch-on'' phase asymptotically into the quasi-stationary, viscous accretion regime. One major question we address is the C-, H-, O-chemistry. The leit-motif of our investigation is the attempt to preserve as much consistency as possible when modelling the hydrodynamical, chemical, transport/mixing processes and their mutual interactions in preplanetary disks. We use an explicit scheme for solving the Navier-Stokes equations combined with an implicit solver for the energy equation. The viscosity coefficient is modelled according to the so-called β-prescription of ``turbulent'' viscosity. In contrast to the well-known α-viscosity, the β-parameterization of the viscosity warrants physical consistency if self-gravitation of the disk material is to be taken into account. However, up to now we have neglected self-gravitation. For the radiative energy transport we have adopted the (grey) Eddington approximation. The opacity is assumed to be caused by microscopic dust particles. Diffusive mixing of the various chemical species is modelled by taking the diffusion coefficient, D, proportional to the (turbulent) viscosity, νturb. For comparison purposes, we have considered two extreme choices of the Schmidt number, S:=νturb/D, that is, S=1 (D=νturb) and S=∞ (D=0, i.e., no diffusive mixing at all), respectively. We have not yet included coagulation processes and grain growth. The main outcome of the 2-D simulations so far carried out is a characteristic circulation pattern of the quasi-stationary accretion flow: Near the disk's equatorial plane which is assumed to be a plane of symmetry the material moves in the outward direction, whereas the accretion flow proper develops in higher altitudes of the disk. Species that are produced or undergo chemical reactions in the warm inner zones of the disk are advectively transported into the cool outer regions. At the same time, they either diffusively mix up with the surrounding material or freeze out on the dust grains to form ``ice''-coated particles. By virtue of the large-scale circulation, which is driven by viscous angular momentum transfer, advective transport dominates diffusive mixing in the outer part of the disk.

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Journal keyword(s): accretion, accretion disks - hydrodynamics - diffusion - astrochemistry - solar system: formation

Simbad objects: 1

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Number of rows : 1

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 1888 1

    Equat.    Gal    SGal    Ecl

C.D.S. - SIMBAD4 rel 1.7 - 2019.08.22CEST23:11:12

Available data : Basic data  •  Identifiers  •  Plot & images  •  Bibliography  •  Measurements  •  External archives  •  Notes  •  Annotations


Basic data :
NAME Orion Nebula Cluster -- Open (galactic) Cluster
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types:
OpC (Ref), Cl* ([C2000b])
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : coordinates error major axis, minor axis (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) :
05 35 00.0 -05 29 00 [ ] E 2007MmSAI..78..628M
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : coordinates error major axis, minor axis (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) :
05 32 32.6 -05 30 55 [ ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : coordinates error major axis, minor axis (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) :
209.0666 -19.4873 [ ]
Syntax of proper motions is : "pm-ra pm-dec [error ellipse] quality bibcode"
  • pm-ra : mu-ra*cos(dec) (expressed in the ICRS system in mas/yr)
  • pm-dec : mu-dec (expressed in the ICRS system in mas/yr)
  • [error ellipse] : error major axis and minor axis (in mas), orientation angle (in deg)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the proper motion reference
Proper motions mas/yr :
2.05 1.56 [1.90 2.75 90] ~ 2014A&A...564A..79D
Syntax of radial velocity (or/and redshift) is : "value [error] (wavelength) quality bibcode"
  • value : radial velocity or/and redshift (Heliocentric frame) according to your Output Options
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  • [error] : error of the corresponding value displayed before
  • (wavelength) : wavelength range of the measurement : Rad, mm, IR, Opt, UV, Xray, Gam or  '∼'(unknown)
  • quality : flag of quality ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the value's origin
Radial velocity / Redshift / cz :
V(km/s) 9.7 [~] / z(~) 0.000032 [~] / cz 9.70 [~]
   D ~
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NAME ONC NAME Ori Cluster NAME Orion Nebula Cluster
GAL 208.9-19.4 NAME Orion Cluster [C2000b] 2

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References (1888 between 1850 and 2019) (Total 1888)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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2019.08.22-23:11:12

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