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

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24 Introduction to interferometry baseline=b Point source at infinity Incoming plane waves ∆θ = 2 slits Fringe spacing λ /b radians Interference pattern (Visibility = 1) λ = Wavelength Point sources at infinity separated by 1/2 the fringe spacing 2 sine waves destructively interfere (Visibility = 0) Figure 2.1: From Monnier (2003). Young’s two-slit interference experiment (monochromatic light) is presented to illustrate the basic principle behind stellar interferometry. On the left is the case for a single point-source, on the right a double source with an angular separation half of the fringes spacing. The interference patterns shown represent the intensity distribution. In this case, the two illumination patters are out of phase of 180 ◦ , cancelling each other out and presenting an uniformly illuminated screen. This simple experiment shows a fundamental property of interference, namely that the contrast of fringes is a function of the geometry of the source. The application of interferometry in astronomy has been firstly proposed by Fizeau in 1868, who suggested to measure the fringes pattern produced by the stellar light to
2.1 A bit of history 25 measure stellar diameters. The practical implementation of this technique arrived many years later with Michelson who, in 1891, measured the angular diameter of Jupiter’s satellites. For the following thirty years astronomical interferometry stalled; only in 1921, Michelson and Pease successfully measured the diameter of the super-giant star Betelgeuse using an interferometer at the Mount Wilson Observatory. While techni- cal difficulties delayed the growth of optical interferometry until the mid-1970’s, radio interferometry had a fast development after the second world war. In 1946, Ryle and Vonderg constructed a radio analogue of the Michelson interferometer and soon discov- ered a number of new cosmic radio sources. During 1950s and 60s, Ryle and Hewish developed the aperture synthesis method at radio wavelengths which allows the source image reconstruction combining the signals from many different pairs of antennas. In the 70s, they applied this method to reproduce a one-mile effective aperture using an array of three antennas with a diameter of 60 feet each. A common technique in aperture synthesis imaging is to use the rotation of the Earth to increase the number of different antenna pairs included in an observation. In the last forty years, aperture synthesis has been widely applied in radio interferometry with the result that astronomical images of good quality can be now obtained (see Chapter 7) Despite the improvement in the radio domain, optical interferometry has only been developed from the mid-1970’s with the advent of new technology: detectors, actuators, servo-control, etc. Labeyrie (1975) was the first to directly combine the light from two separated small telescopes at the Nice observatory. In the 1980s, the aperture synthesis technique was extended to visible and infrared astronomy by the Cavendish Astro- physics Group, providing the first very high resolution images of nearby stars. These development allowed the planning and construction in the mid-90s of several optical in- terferometers. In particular, with the ESO Very Large Telescope Interferometer (VLTI), the Keck Interferometer (KI) and the CHARA array, optical interferometry is becoming a familiar technique for an increasing number of astronomers.
Page 1: Università degli Studi di Milano F
Page 5 and 6: CONTENTS I Introduction 1 1 Scienti
Page 7 and 8: CONTENTS v 4.5 Comparison with prev
Page 9: Part I Introduction
Page 12 and 13: 4 Scientific overview the critical
Page 14 and 15: 6 Scientific overview Log νFν Log
Page 16 and 17: 8 Scientific overview are the subje
Page 18 and 19: 10 Scientific overview disk regions
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Page 22 and 23: 14 Scientific overview depleted inn
Page 24 and 25: 16 Scientific overview the gas and
Page 26 and 27: 18 Scientific overview Figure 1.3:
Page 28 and 29: 20 Scientific overview We propose a
Page 31: CHAPTER 2 2.1 A bit of history Intr
Page 35 and 36: 2.2 Basic principle of astronomical
Page 37 and 38: 2.3 Optical versus millimeter inter
Page 43 and 44: 2.4 Introduction to modelling techn
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Page 49 and 50: CHAPTER 3 The shape of the inner ri
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
Page 71 and 72: 3.6 Appendix 63 However, the bright
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74 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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