Chemical characterization of the first stages of protoplanetary disk formation Ugo Hincelin – 25 th June 2010 Collaborators :Valentine Wakelam (supervisor)

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


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…)


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


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 1 000 000 yr

Abundance n(i)/nHTemperature and density

evolution from Visser’s trajectory


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 1 000 000 yr


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


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


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



parametric functions – cloud of 106yr

testing changes in thermal and density history – temperature of the shock


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



parametric functions – cloud of 106yr

testing changes in thermal and density history – time of the shock


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


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


Thank you for your attention

Documents

Chemical characterization of the first stages of protoplanetary disk formation Ugo Hincelin – 25 th June 2010 Collaborators :Valentine Wakelam (supervisor)