Polarimetry of Hot-Jupiter Systems and Radiative Transfer Models of Planetary Atmospheres
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University of New South Wales Doctoral Thesis Polarimetry of hot-Jupiter systems and radiative transfer models of planetary atmospheres Author: Supervisor: Kimberly Bott Prof. Jeremy Bailey Co-supervisor: Prof. Chris Tinney A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in the Department of Astrophysics School of Physics March 2017 PLEASE TYPE THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: Bott First name: Kimberly Other name/s: Abbreviation for degree as given in the University calendar: PhD School: Physics Faculty: Science Title: Polarimetry of hot-Jupiter systems and radiative transfer models of planetary atmospheres Abstract 350 words maximum: (PLEASE TYPE) Thousands of exoplanets and planet candidates have been detected. The next important step in the contexts of astrobiology, planetary classification and planet formation is to characterise them. This thesis aims to provide further characterisation to four hot Jupiter exoplanets: the relatively well-characterised HD 189733 b, W ASF- l 8b which is nearly large enough to be a brown dwarf, and two minimally characterised non-transiting hot Jupiters: HD 179949b and tau Bootis b. For the transiting planets, this is done through two means. First, published data from previous observations of the secondary eclipse (and transit for HD 189733b) are compared to models created with the Versatile Software for the Transferof Atmospheric Radiation (VST AR). Second, new polarimetric observations from the High Precision Polarimetric Instrument are compared to Lambert-Rayleigh polarised light phase curves. For the non-transiting planets, only the polarimetric measurements are compared to models, but toy radiative transfermodels are produced for concept. As an introduction to radiative transfermodels, VSTAR is applied to the planet Uranus to measure its D/H isotope ratio. A preliminary value is derived for D/H in one part of the atmosphere. Fitting a single atmospheric model to the transmitted, reflected, and emitted light, I confirm the presence of water and carbon monoxide on HD 189733b, and present a new temperature profileand cloud profilefor the planet. ForWASP- 18b, I confirm the general shape of the temperature profile. No conclusions can be drawn from the polarimetric measurements for the non-transiting planets. I detect a possible variation with phase for transiting planet W ASP-l 8b but cannot confirm at this time. Alternative sources to the planet are discussed. For HD 189733b, I detect possible variability in the polarised light at the scale expected for the planet. However, the data are also statistically consistent with no variability and do not match the phase of the planet. This thesis demonstrates the value of robust radiative transfer models and of polarized light detections to the characterisation of the atmospheres and orbital elements of exoplanets. Further polarimetric measurements to be taken by the HIPP! team in the near future will provide useful characterisation of these planets. Declaration relating to disposition of project thesis/dissertation I hereby grant to the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all property rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or partof this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstracts International (this is applicable to doctoral theses only). Date The University recognises that there may be exceptional circumstances requiring restric ions on copying or conditions on use. Requests for restriction for a period of up to 2 years must be made in writing. Requests for a longer period of restriction may be considered in exceptional circumstances and re uire the a roval of the Dean of Graduate Research. FOR OFFICE USE ONLY Date of completion of requirements for Award: COPYRIGHT STATEMENT 'I hereby grant the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstract International (this is applicable to doctoral theses only). I have either used no substantial portions of copyright material in my thesis or I have obtained permission to use copyright material; where permission has not been granted I have applied/will apply for a partial restriction of the digital copy of my thesis or dissertation.' Signed Date AUTHENTICITY STATEMENT 'I certify that the Library deposit digital copy is a direct equivalent of the final officially approved version of my thesis. No emendation of content has occurred and if there are any minor variations in formatting, they are the result of the conversion to digital format.' Signed Date ORIGINALITY STATEMENT ‘I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged.’ Signed …………………………………………….............. Date …………………………………………….............. \We don't want to conquer the cosmos, we simply want to extend the boundaries of Earth to the frontiers of the cosmos. For us, such and such a planet is as arid as the Sahara, another as frozen as the North Pole, yet another as lush as the Amazon basin. We are humanitarian and chivalrous; we don't want to enslave other races, we simply want to bequeath them our values and take over their heritage in exchange. We think of ourselves as the Knights of the Holy Contact. This is another lie. We are only seeking Man. We have no need of other worlds. A single world, our own, suffices us; but we can't accept it for what it is. We are searching for an ideal image of our own world: we go in quest of a planet, a civilization superior to our own but developed on the basis of a prototype of our primeval past." Stanis law Lem (Solaris) \Finally, from so little sleeping and so much reading, his brain dried up and he went completely out of his mind." Miguel de Cervantes (Don Quixote) UNIVERSITY OF NEW SOUTH WALES Abstract Polarimetry of hot-Jupiter systems and radiative transfer models of planetary atmospheres by Kimberly Bott Thousands of exoplanets and planet candidates have been detected. The next important step in the contexts of astrobiology, planetary classification and planet formation is to characterise them. This thesis aims to provide further characterisation to four hot Jupiter exoplanets: the relatively well-characterised HD 189733b, WASP-18b which is nearly large enough to be a brown dwarf, and two minimally characterised non-transiting hot Jupiters: HD 179949b and τ Bootis b. For the transiting planets, this is done through two means. First, published data from previous observations of the secondary eclipse (and transit for HD 189733b) are com- pared to models created with the Versatile Software for the Transfer of Atmospheric Radiation (VSTAR). Second, new polarimetric observations from the HIgh Precision Po- larimetric Instrument are compared to Lambert-Rayleigh polarised light phase curves. For the non-transiting planets, only the polarimetric measurements are compared to models, but toy radiative transfer models are produced for concept. As an introduction to radiative transfer models, VSTAR is applied to the planet Uranus to measure its D/H isotope ratio. A preliminary value is derived for D/H in one part of the atmosphere. Fitting a single atmospheric model to the transmitted, reflected, and emitted light, I confirm the presence of water and carbon monoxide on HD 189733b, and present a new temperature profile and cloud profile for the planet. For WASP-18b, I confirm the general shape of the temperature profile. No conclusions can be drawn from the polarimetric measurements for the non-transiting planets. I detect a possible variation with phase for transiting planet WASP-18b but cannot confirm at this time. Alternative sources to the planet are discussed. For HD 189733b, I detect possible variability in the polarised light at the scale expected for the planet. However, the data are also statistically consistent with no variability and do not match the phase of the planet. This thesis demonstrates the value of robust radiative transfer models and of polarised light detections to the characterisation of the atmospheres and orbital elements of exo- planets. Further polarimetric measurements to be taken by the HIPPI team in the near future will provide useful characterisation of these planets. Acknowledgements I'd like to thank my thesis advisor Jeremy Bailey for his guidance and support. Thank you for being accessable without being imperious. Thank you also for finding ways to aid my studies by ensuring my environment was as stable and condusive to research as possible.