chemical characterization of the first stages of protoplanetary disk formation ugo hincelin – 25...
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Chemical characterization of the first stages of protoplanetary disk formation
Ugo Hincelin – 25th June 2010
Collaborators : Valentine Wakelam (supervisor)Stéphane Guilloteau (supervisor)Franck Hersant
Astrochemistry of Molecules and ORigins of planetary systems (AMOR)Laboratoire d’Astrophysique de Bordeaux, France
Introduction Results Prospects
Disk formation
Is there a link between interstellar matter & disk matter?
Are initial conditions of disk formation important for the disk chemical composition?
Is thermal history of disk formation important?
Method
Steps: simulate chemistry during different phases (diffuse cloud molecular cloud disk)
How? using chemical gas-grain model Nautilus (Hersant et al. 2009, based on Herbst’s team)
T = 10Kn = 2.104 cm-3
different ages
T = f(time)nH = f(time)
<-- initial chemical composition of a diffuse cloud
different evolution scenarios
--> final chemical composition of molecular cloud = initial conditions for disk formation
Introduction Results Prospects
Modelling steps
Method
--> chemical composition of the disk
gas cell trajectoryarrival at 30AU from the
protostar at 2.5x105 yr
temperature and density along trajectory = parameters for Nautilus
(Visser et al. 2009)
R (AU)
z (AU)
Scenarios, from molecular cloud collapse to disk, extracted from hydrodynamic models (Visser et al. 2009…)
Introduction Results Prospects
density & temperature profiles
Method
List of models used
3 models : testing the initial conditions1 trajectory evolution of T & ndifferent initial conditions for disk formation : varying the age of the molecular
cloud1) 104
2) 105
3) 106 years old
2 models : testing the evolution ‘s impact of the temperature and the densitymolecular cloud : 105 years old1) 1 trajectory evolution of T & n2) no evolution of T & n
5 models : testing changes in thermal and density historymolecular cloud : 106 years old4) temperature of the accretion shock (100K & 780K)5) time of the shock (early & late)6) temperature decreasing after the accretion shock
Introduction Results Prospects
list of models
Method
About one order of magnitude difference in the abundances of a lot of species when varying initial conditions
Final chemical composition of the disk is influenced by the age of the parent cloud
Chemistry is not at equilibrium time = important factor
H2CO = tracer of the age of the parent cloud?
Dependence of the disk chemical composition on initial conditions (age of parent cloud)
H2OH2O2
COCO2
CH4C2H2
C2H6
CH3C2H
CH3OH
H2COHCOOH
HCOOCH3
CH3CHOCH3OCH3
NH2CHO
NH3
HCN
HNCOHNC
CH3CN
HC3N
10E-1810E-17
10E-1610E-15
10E-1410E-13
10E-1210E-11
10E-1010E-09
10E-0810E-07
10E-0610E-05
10E-04
disk chemical composition
molecular cloud 10 000 yr
molecular cloud 100 000 yr
molecular cloud 1 000 000 yr
Abundance n(i)/nHTemperature and density
evolution from Visser’s trajectory
Introduction Results Prospects
testing the initial conditions
Method
(Bockelée-Morvan et al. 2004)
- Similar abundances for some species (C2H2, H2CO…)
- Little CO on grain : disk temperature too high- Lot of CO2 in 1 case : OH + CO CO2 + H (efficient reaction)
H2O
CO
CO2
CH4
C2H2
C2H6
CH3OH
H2CO
HCOOH
HCOOCH3
CH3CHO
NH2CHO
NH3
HCN
HNCO
HNC
CH3CN
HC3N
1E-3 1E-2 1E-1 1E+0 1E+1 1E+2
Abundances relative to water in disk
molecular cloud 10 000 yr
molecular cloud 100 000 yr
molecular cloud 1 000 000 yr
Introduction Results Prospects
testing the initial conditions – comparison with comets composition
Method
------ model with evolution for T & n (Visser’s trajectory) model without evolution for T & n
thermal and density history of gas and dust changes the final chemical composition of the disk
testing thermal and density history
testing thermal and density history
Introduction Results ProspectsMethod
parametric functions for the temperature and density profiles
minimal density
maximal density
Time of the transitio
n
time of the shock
Shocktemperatur
e
final temperatur
e
testing changes in thermal and density history
Introduction Results ProspectsMethod
H2O
CO
CO2
CH4
C2H2
C2H6
CH3OH
H2CO
HCOOH
HCOOCH3
CH3CHO
NH2CHO
NH3
HCN
HNCO
HNC
CH3CN
HC3N
1,00E-03 1,00E-02 1,00E-01 1,00E+00 1,00E+01 1,00E+02
Abundances relative to water
CO abundance reproducedResults closer to comets composition (13/17 abundances reproduced within 1 order of magnitude)
use of Visser’s temperature profile with final decrease – cloud of 106yr
testing changes in thermal and density history – temperature decreased at the end of the disk formation
Introduction Results ProspectsMethod
No big changes except for some species good for identification of tracers
HCOOCH3, a tracer of temperature of the shock?
JH2O
JH2O2
JCO
JCO2
JCH4
JC2H2
JC2H6
JC3H4
JCH4O
JH2CO
JCH2O2
JHCOOCH3
JC2H4O
JCH3OCH3
JNH2CHO
JNH3
JHCN
JHNCO
JHNC
JC2H3N
JHC3N
1,0E-111,0E-10
1,0E-091,0E-08
1,0E-071,0E-06
1,0E-051,0E-04
1,0E-03
abundances relative to nH total
max temperature = 40K
max temperature = 100K
max temperature = 1000K
parametric functions – cloud of 106yr
testing changes in thermal and density history – temperature of the shock
Introduction Results ProspectsMethod
Again no big changes except for some species good for identification of tracers
HC3N and C2H2, tracers of the shock of the time?
JH2O
JH2O2
JCO
JCO2
JCH4
JC2H2
JC2H6
JC3H4
JCH4O
JH2CO
JCH2O2
JHCOOCH3
JC2H4O
JCH3OCH3
JNH2CHO
JNH3
JHCN
JHNCO
JHNC
JC2H3N
JHC3N
1,0E-121,0E-11
1,0E-101,0E-09
1,0E-081,0E-07
1,0E-061,0E-05
1,0E-041,0E-03
abundances relative to nH total
shock time = 50 000yr
shock time = 133 000yr
shock time = 225 000yr
parametric functions – cloud of 106yr
testing changes in thermal and density history – time of the shock
Introduction Results ProspectsMethod
Conclusion :Chemical composition of the disk is sensitive to the density and thermal historySome tracers would give us some information about the thermal history of the diskChemical composition of comets seems to be a melting pot of matter from different locations in the disk (and envelope?)…
Prospects :Test variation on the temperature peak width ongoing workAdd a high temperature network in chemical model to better simulate warm regionsTest other trajectories and link parametric profiles with trajectories
Introduction Results ProspectsMethod
Conclusion :Chemical composition of the disk is sensitive to the density and thermal historySome tracers would give us some information about the thermal history of the diskChemical composition of comets seems to be a melting pot of matter from different locations in the disk (and envelope?)…
Prospects :Test variation on the temperature peak width ongoing workAdd a high temperature network in chemical model to better simulate warm regionsTest other trajectories and link parametric profiles with trajectories
Introduction Results ProspectsMethod
Thank you for your attention