Interferometric observations of pre-main sequence disks - Caltech ...

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12 Scientific overview Figure 1.2: From Dullemond et al. (2006). Build-up of the SED of a flaring circumstellar disk and the origin of various components: the near infrared bump is supposed to originate in the puffed-up inner rim, the infrared dust features (as the silicate ones between 10µm and 20µm) from the warm surface layer, and the underlying continuum from the deeper and cooler disk regions. Typically the near and mid-infrared emission comes from small radii, while the far- infrared and the millimeter emission come from the outer disk regions. radiation and the disk is stronger and where the magnetic field is supposed to drive the often observed outflows and jets that propagate perpendicularly to the disk plane. In the innermost region of the disk, where the temperature is higher than∼1500 K, most of the dust sublimates (Pollack et al., 1994) and the opacity undergoes a strong discontinuity (Natta et al., 2001; Dullemond et al., 2001). If the gas inside the dust sublimation radius
1.2 Disk structure in the pre-main sequence phase 13 absorbs a negligible amount of stellar radiation, the dust inner rim is perpendicularly illuminated by the central star and is expected to be hotter and higher, i.e. with an higher pressure scale, than a standard reprocessing disk. The resulting puffed-up inner rim dominates the near-infrared emission and naturally explains the strong near-infrared excess observed in most of the SEDs of HAe and TTS stars. The presence of a puffed-up inner rim can influence the structure of the outer regions of the disk shadowing the dust from the direct stellar radiation. Meeus et al. (2001, 2003) divided the SEDs of HAe stars into two groups: those with strong far-infrared flux (group I) and those with weak infrared flux (group II), suggesting that the latter are characterized by a disk that lies in the shadow of the puffed-up inner rim. Although the real existence of the puffed-up inner rim is still under debate (Vinkovic et al., 2006), model predictions are in good agreement with the spatially resolved near infrared interferometric observations of a number of HAe and TTS stars (see the review of Millan-Gabet et al. 2006). The second part of the thesis (Chapters 3, 4 and 5) is dedicated to the discussion of the structure of the puffed-up inner rim and to the analysis of interferometric observations of the inner disk. The structure of the gaseous disk inside the dust sublimation radius is still poorly known (see the review of Najita et al., 2006). Existing high resolution spectroscopic observations of CO and water near infrared emission lines indicate that the gas extends very close to the central star, probably until the distance at which the gaseous disk is truncated by the stellar magnetic field lines (Shu et al., 1994). Inside this point, typically located at few stellar radii, the gas moves along the magnetic field lines and accretes on the central star emitting the UV radiation usually observed in HAe and TTS spectra as UV veiling (Hartman et al., 1998; Bouvier et al., 2006). The accreting gas is also supposed to be responsible for the hydrogen recombination lines (Hα, Brγ, Paβ, etc) characteristic of most HAe and TTS. Both the amount of veiling and the hydrogen line intensities depend on the accreting gas density and are used to measure the mass accretion rate (Muzerolle et al., 2001; Natta et al., 2006). Chapter 6 is dedicated to the spectrally resolved near infrared interferometric observations of the gas in the dust-
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Page 5 and 6: CONTENTS I Introduction 1 1 Scienti
Page 7 and 8: CONTENTS v 4.5 Comparison with prev
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Page 12 and 13: 4 Scientific overview the critical
Page 14 and 15: 6 Scientific overview Log νFν Log
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Page 28 and 29: 20 Scientific overview We propose a
Page 31 and 32: CHAPTER 2 2.1 A bit of history Intr
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Page 35 and 36: 2.2 Basic principle of astronomical
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Page 43 and 44: 2.4 Introduction to modelling techn
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Page 51 and 52: 3.1 Introduction 43 Tauri stars (Ei
Page 53 and 54: 3.2 Model description 45 adapt the
Page 55 and 56: 3.2 Model description 47 log(δR/R
Page 57 and 58: 3.2 Model description 49 the pressu
Page 59 and 60: 3.3 Results 51 Photospherical heigh
Page 61 and 62: 3.3 Results 53 ever, is sufficientl
Page 63 and 64: 3.3 Results 55 Sec. 3.3.1 (see Fig.
Page 65 and 66: 3.4 Discussion 57 the value ofǫ, t
Page 67 and 68: 3.4 Discussion 59 sample of Fig. 3.
Page 69 and 70: 3.5 Summary and conclusions 61 R in
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3.6 Appendix 63 However, the bright
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3.6 Appendix 65 Figure 3.9: Left pa
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68 Large dust grains in the inner r
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Face-on disk image Baseline (m) V 2
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V 2 1 0.8 0.6 0.4 0.2 0 0 50 100 15
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V 2 1 0.8 0.6 0.4 0.2 0 0 50 100 15
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CHAPTER 5 More on the “puffed-up
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5.1 Fuzzy and sharp rims 97 opacity
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5.2 New shapes for the rim 99 grain
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5.3 New observational results 101 (
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5.3 New observational results 103 w
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CHAPTER 6 Constraining the wind lau
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6.1 Introduction 109 λ Fλ (erg cm
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6.2 Observations and data reduction
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6.3 Results and discussions 113 V V
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6.4 Conclusions 115 note however th
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Part IV The structure of the outer
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120 The keplerian disk of HD 163296
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Part V Conclusions and future prosp
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152 Summary and Conclusions ∼1 an
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154 Summary and Conclusions disk in
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CHAPTER 9 Future developments As my
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9.1 Gas in the inner disk of Herbig
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9.2 Probing planet formation throug
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Published papers • Isella, A.; Te
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172 BIBLIOGRAPHY [2000] Bodenheimer
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174 BIBLIOGRAPHY [2004] Gail H.-P.,
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176 BIBLIOGRAPHY Arizona Press, Tuc
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178 BIBLIOGRAPHY [2001] Thompson A.
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