Citation
Jonkheid, B. J. (2006, June 28). Chemistry in evolving protoplanetary disks. Retrieved from https://hdl.handle.net/1887/4451
Version: Corrected Publisher’s Version
License: Licence agreement concerning inclusion of doctoral thesisin the Institutional Repository of the University of Leiden Downloaded from: https://hdl.handle.net/1887/4451
Contents
1 Introduction 1
1.1 Low mass star formation . . . 1
1.2 Disk evolution and planet formation . . . 1
1.2.1 Global evolution . . . 1
1.2.2 Dust evolution . . . 3
1.3 Photodissociation regions . . . 6
1.4 Disk chemistry . . . 7
1.5 Outline of the thesis . . . 9
1.6 Main results of the thesis . . . 11
2 A PDR code comparison study 15 2.1 Introduction . . . 16
2.2 The physics of PDRs . . . 17
2.3 Modeling of PDRs . . . 18
2.4 Description of sensitivities and pitfalls . . . 20
2.4.1 Model geometry . . . 20
2.4.2 Chemistry . . . 21
2.4.3 Heating and cooling . . . 25
2.4.4 Grain properties . . . 26
2.4.5 Radiative transfer . . . 27
2.4.6 Ionization rate . . . 27
2.5 Description of the benchmark models . . . 29
2.5.1 PDR code characteristics . . . 29
2.5.2 Benchmark frame and input values . . . 31
2.6 Results . . . 33
2.6.1 Models with constant temperature F1-F4 . . . 34
2.6.2 Models with variable temperature V1-V4 . . . 39
2.6.3 Further thermal balance tests . . . 43
2.7 Concluding remarks . . . 45
3 The gas temperature in flaring disks around pre-main sequence stars 53 3.1 Introduction . . . 53
3.2 Calculating the gas temperature . . . 55
3.2.2 Chemistry . . . 57 3.2.3 Thermal balance . . . 59 3.2.4 Dust settling . . . 59 3.3 Results . . . 62 3.3.1 Temperature . . . 62 3.3.2 Chemistry . . . 66 3.3.3 Line intensities . . . 69 3.4 Discussion . . . 69
3.4.1 Limitations of the 1+1-D model . . . 69
3.4.2 Effects of gas-dust coupling . . . 70
3.4.3 Effects of the radiation field . . . 70
3.5 Conclusions . . . 71
Appendix . . . 75
A. Heating processes . . . 75
B. Cooling processes . . . 77
4 Modeling the chemistry of the HD 141569A transitional disk 79 4.1 Introduction . . . 79 4.2 Model . . . 81 4.2.1 Input . . . 81 4.2.2 Treatment of dust . . . 85 4.3 Results . . . 86 4.3.1 Chemistry . . . 86 4.3.2 Temperature . . . 90
4.4 Constraining the gas mass . . . 91
4.4.1 CO lines . . . 91
4.4.2 Other emission lines . . . 94
4.4.3 Gas/dust ratio . . . 94
4.4.4 Second generation gas? . . . 95
4.5 Conclusions . . . 95
5 Chemistry and line emission from evolving Herbig Ae disks 99 5.1 Introduction . . . 99
5.2 Model . . . 101
5.3 Results and discussion . . . 106
5.3.1 Gas temperature . . . 106
5.3.2 Chemistry . . . 107
5.3.3 Column densities . . . 111
5.3.4 Atomic and molecular lines . . . 113
Contents
Nederlandse samenvatting 123
Curriculum Vitae 129
Nawoord 131