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Dissertation DISSERTATION Titel der Dissertation „Shaping the slow winds of Asymptotic Giant Branch stars in binary systems“ Verfasser Mag. Andreas Mayer, Bakk. angestrebter akademischer Grad Doktor der Naturwissenschaften (Dr.rer.nat.) Wien, 2015 Studienkennzahl lt. Studienblatt: A 796 605 413 Dissertationsgebiet lt. Studienblatt: Astronomie Betreuerin / Betreuer: Ao. Univ.-Prof. Dr. Franz Kerschbaum Reicher Mann und armer Mann Standen da und sahn sich an. Und der Arme sagte bleich: W¨arich nicht arm, w¨arstdu nicht reich. Bertolt Brecht { \Alfabet" (1934) Contents List of Figures 7 List of Tables 8 1. Introduction 9 1.1. Herschel Space Observatory . 9 1.1.1. Spacecraft . 10 1.1.2. The Photodetector Array Camera and Spectrometer . 12 1.1.3. Data processing . 14 1.1.4. Mass-loss of Evolved StarS (MESS) program . 19 1.2. Asymptotic giant branch stars . 20 1.2.1. Stellar structure and evolution . 22 1.2.2. Dust formation & mass loss . 27 1.2.3. Observational properties . 31 1.3. AGB stars in binary systems . 34 1.3.1. Mass transfer in binary systems . 36 1.3.2. Observing binary AGB star systems . 39 1.4. Stellar winds . 42 1.4.1. Interaction of two winds: detached shells . 46 1.4.2. Interaction with the interstellar medium: bow shocks . 48 1.4.3. Interaction with a companion: Archimedean spirals . 52 2. Publications 59 2.1. Herschel's view into Mira's head . 61 2.2. Large-scale environments of binary AGB stars - I. 66 2.3. Large-scale environments of binary AGB stars - II. 82 2.4. Publications as co-author . 97 2.4.1. A far-infrared survey of bow shocks and detached shells around AGB stars and red supergiants . 97 2.4.2. Dusty shells surrounding the carbon variables S Scuti and RT Capricorni . 99 2.4.3. Improving Herschel imaging datasets . 100 2.4.4. The wonderful complexity of the Mira AB system . 101 2.4.5. Dissecting the AGB star L2 Puppis . 103 3. Conclusion & Outlook 105 3.1. Remaining binary objects of the MESS sample . 108 3.1.1. θ Apodis . 108 3.1.2. EP Aquarii . 114 3.1.3. IRC +10 216 (CW Leonis) . 118 3.1.4. o1 Orionis . 120 3.1.5. Y Lyncis . 122 3.1.6. TW Horologii . 123 3.1.7. U Camelopardis . 124 3.1.8. R Sculptoris . 126 3.1.9. V Hydræ . 129 3.1.10. VY Ursæ Majoris . 130 3.1.11. TX Camelopardis . 132 3.1.12. V Eridani . 133 3.1.13. CIT 6 (RW Leonis Minoris) . 134 3.1.14. AFGL 3068 (LL Pegasi) . 137 3.1.15. VY Canis Majoris . 139 Bibliography 141 A. Appendix 157 A.1. Kurzfassung . 157 A.2. Abstract . 158 A.3. A&A reprint permission . 159 A.4. Abbreviations . 160 A.5. Constants . 162 A.6. Observing proposal for ESO P93A . 162 B. Curriculum Vitæ 175 B.1. Publication list . 177 C. Acknowledgements 181 List of Figures 1.1. Herschel Space Observatory . 11 1.2. PACS layout and light path through the instrument . 12 1.3. Herschel's scan map technique . 13 1.4. Herschel/PACS model PSF . 18 1.5. Evolutionary track of a 1 M star on the HRD . 21 1.6. Processes in the MS and AGB phase according to mass . 24 1.7. Internal structure of a 2 M AGB star . 26 1.8. Movement of atmospheric layers . 29 1.9. Schematic view of a circumstellar envelope . 30 1.10. Evolution of a low mass binary system . 33 1.11. Orbital period distribution of nearby binary systems . 35 1.12. Roche equipotential surface . 37 1.13. Concept of a stellar wind bubble . 43 1.14. IRAS two-colour diagram of AGB stars . 44 1.15. Herschel/PACS images of S Scuti . 47 1.16. Thin shell model of a bow shock . 49 1.17. Herschel/PACS images of TX Piscium and X Herculis . 51 1.18. Velocity field of wind accretion around secondary star . 53 1.19. Model of a wide binary spiral pattern . 54 1.20. Two examples of spiral patterns around AGB stars . 55 3.1. Herschel/PACS images of θ Apodis . 109 3.2. Positional data of θ Apodis . 110 3.3. Contour plot of θ Apodis . 111 3.4. Herschel/PACS images of EP Aquarii . 115 3.5. Intensity plots of EP Aquarii . 116 3.6. Herschel/PACS & SPIRE images of IRC +10 216 . 118 3.7. Herschel/PACS images of o1 Orionis . 120 3.8. Herschel/PACS images of Y Lyncis . 122 3.9. Herschel/PACS images of TW Horologii . 123 3.10. Herschel/PACS images of U Camelopardis . 124 3.11. Illustration of the environment of R Sculptoris . 126 3.12. Herschel/PACS images of R Sculptoris . 127 7 3.13. Herschel/PACS images of V Hyadræ . 129 3.14. Herschel/PACS images of VY Ursæ Majoris . 130 3.15. Herschel/PACS images of TX Camelopardis . 132 3.16. Herschel/PACS images of V Eridani . 133 3.17. VLA velocity channel maps of CIT 6 . 134 3.18. Herschel/PACS images of CIT 6 . 135 3.19. HST image of AFGL 3068 . 137 3.20. Herschel/PACS images of AFGL 3068 . 138 3.21. Herschel/PACS images of VY Canis Majoris . 140 List of Tables 1.1. Most abundant molecules produced in AGB stars . 28 3.1. Positional data of θ Apodis . 112 3.2. Position angles of bipolar outflow and proper motion direction . 113 8 CHAPTER 1 Introduction 1.1. Herschel Space Observatory The thesis at hand is an observational study of the interactions that occur in the winds of asymptotic giant branch (AGB) stars and is based on obser- vations carried out with the Herschel Space Observatory (Herschel; Pilbratt et al. 2010). Herschel is a space mission led by the European Space Agency (ESA) and dedicated to the far-infrared (IR) and sub-millimetre wavelength range, whose exploration was included in ESA's long-term plan Horizon 2000 (Longdon 1984). By this time, it was called the Far-InfraRed and Submillime- tre space Telescope (FIRST) until it received its present name Herschel in the year 2000; named after Friedrich Wilhelm Herschel (1738{1822), the discoverer of the infrared radiation. The Herschel mission was chosen as the successor of the Infrared Space Observatory (ISO; 1995{1998) and the realisation of the mission was decided in 1993 as the fourth cornerstone mission of ESA, after the X-ray Multi-Mirror-Mission (XMM-Newton; 1999{present), the Solar and Heliospheric Observatory (SOHO; 1995{present), and Rosetta (2004{present). Shortly after, the industrial production of the spacecraft began with a budget of 1.1 billion Euro. Given the high costs of space missions, the reasons to operate a telescope outside earth must be vital and are found in the properties of the earth's atmo- sphere. On the one hand, the atmospheric windows only allow ground-based observations in certain wavelength ranges (optical, near- to mid-infrared, and radio), while photons of other energies are absorbed and scattered by several molecules like ozone, carbon dioxide, and water (vapour) in the earth's at- mosphere. On the other hand, the thermal conditions and instability of the atmosphere hinders ground-based observations. This is especially the case in the far-IR regime (λ > 15 µm), where the thermal emission of the atmosphere dominates the observations. To explore the universe in this wavelength range means to reveal its cool and dusty places. The far-infrared covers a wavelength 9 1.1. Herschel Space Observatory range of roughly 15{1000 µm, equivalent to the peaks of the black body radi- ation curve between 300 K and 3 K. This is the temperature domain of newly born stars, planets and galaxies, active galactic nuclei (AGN), and evolved stars. Prior IR space missions like the Infrared Astronomical Satellite (IRAS), ISO, Spitzer Space Observatory, and AKARI delivered spectacular results in these scientific fields. Herschel is able to add a new level of detail to the far-IR universe due to its high sensitivity and spatial resolution. With a wavelength range of 55{671 µm, it is the first mission going beyond 200 µm (besides the Cosmic Background Explorer (COBE) and Wilkinson Microwave Anisotropy Probe (WMAP), which are used solely for cosmological studies). On 14 May 2009, Herschel was finally sent to space with an Ariane 5-ECA rocket1. After the separation from the carrier rocket, Herschel was manoeuvred 9 to the second Lagrange point (L2), which is located ≈ 1:5 × 10 m behind the earth, as seen from the sun. L2 has the advantage that the sun, earth, and moon are on the same side which is handy in the sense that a sunshade is able to protect the spacecraft effectively. At this location, the spacecraft moves with the same orbital period as the earth. On 14 June 2009, while moving to L2, the Photodetector Array Camera & Spectrometer (PACS) on-board Herschel obtained first light: an image of M51, the Whirlpool Galaxy. After several commissioning phases the first routine operations were executed on 18 October 2009. In March 2013, nearly four years after launch and 3.5 years of successful observations, the liquid helium needed to cool the Herschel detectors was almost completely evaporated. This lack of helium prevented the detectors from working accurately and on 29 April 2013 ESA declared the Herschel mission to be completed. 1.1.1. Spacecraft The Herschel Space Observatory has a total size of about 4 m × 4 m × 7 m with a mass of 3400 kg at launch. This includes 600 kg of liquid helium that is used to cool the instruments2.
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