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Amplitude and Frequency Modulations of Oscillation Modes in Hot B Subdwarf and White Dwarf Stars from Kepler Photometry Weikai Zong

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Amplitude and Frequency Modulations of Oscillation Modes in Hot B Subdwarf and White Dwarf Stars from Kepler Photometry Weikai Zong Amplitude and frequency modulations of oscillation modes in hot B subdwarf and white dwarf stars from Kepler photometry Weikai Zong To cite this version: Weikai Zong. Amplitude and frequency modulations of oscillation modes in hot B subdwarf and white dwarf stars from Kepler photometry. Astrophysics [astro-ph]. Université Toulouse 3 Paul Sabatier, 2016. English. tel-01434986 HAL Id: tel-01434986 https://tel.archives-ouvertes.fr/tel-01434986 Submitted on 13 Jan 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. THÈSETHÈSE En vue de l’obtention du DOCTORAT DE L’UNIVERSITÉ DE TOULOUSE Délivré par : l’Université Toulouse 3 Paul Sabatier (UT3 Paul Sabatier) Présentée et soutenue le 17/10/2016 par : Weikai ZONG Amplitude and frequency modulations of oscillation modes in hot B subdwarf and white dwarf stars from Kepler photometry JURY Dr. Marie-Jo Goupil Astronome Rapporteur Dr. Roberto Silvotti Chercheur Rapporteur Prof. Jianning FU Professeur Examinateur Prof. Sylvie VAUCLAIR Professeur d’Université Président Dr. Gérard VAUCLAIR Directeur de Recherche Co-Directeur de thèse Dr. Stéphane Chargé de Recherche Directeur de thèse CHARPINET École doctorale et spécialité : SDU2E : Astrophysique, Sciences de l’Espace, Planétologie Unité de Recherche : Institut de Recherche en Astrophysique et Planétologie (UMR 5277) Directeur de Thèse : Dr. Stéphane CHARPINET et Dr. Gérard VAUCLAIR Rapporteurs : Dr. Marie-Jo GOUPIL et Dr. Roberto SILVOTTI i Acknowledgements It is three years plus one month to fulfill the project aiming at searching for and charac- terizing amplitude and frequency modulations in oscillation modes in these fantasy stars that observed by the magnificent telescope KEPLER. I am very glad to see that our results may give a very tiny impetus on the way to see the nonlinear things in stellar pulsation theory. Now it is properly the time to thank many people who help me a lot during the last three years of being a Ph.d candidate in Toulouse, la Ville Rose. First and foremost, my thanks are given to my supervisor, Stéphane Charpinet, for his pa- tience, guidance, support, and inspiration that make this thesis possible. When I retrospect back the days, I am so grateful to be a student of Stéphane. He is a very special kind of su- pervisor, who always shows great passion on research. He is very knowledgable in our field and always answers my questions and inspires me with new ideas. I really learn quite a lot from him about how to become a good researcher. My great thanks are also given to Gérard Vauclair, my co-supervisor, who is a gracious person. He has many open minds on this field, or concretely, novel ideas on the nonlinear physics in stars. These knowledge brings me confidence on the way to firmly insist my research when I have to face to hard things. Both Stéphane and Gérard had never said any hard word on my works and always encourage me to progress in my study. I am very appreciate for this. This thesis cannot be accomplished without the unprecedented high-quality and long-duration data from the KEPLER space telescope. It is funded by the NASA’s Science Mission Directo- rate. I gratefully acknowledge the KEPLER Science Team and all those who have contributed to making the mission possible. The works presented in the thesis are also contributed by two other collaborators, Noemi Giammichele and Valerie Van Grootel. I must thank their independent calculation of theore- tical models on the white dwarf star that makes it comparing with the observed modulations possible. Noemi just joined our group as a postdoctoral around her defense in Montréal. I thank my thesis and candidacy defense committee, which is composed of Marie-jo Goupil, Roberto Silvotti, Sylvie Vauclair, Jianning Fu, Gérard and Stéphane, for their valuable time on evaluating the work and for their important suggestions and comments to my future career. I thank the reporters, Marie-jo and Roberto, for their well-written reviews, for the positive view on the discovered mode modulations and the theoretical interpretations. Sylvie, she is the pre- sident of my examinations for three times continuously, who see my progresses during these three years, from a freshmen to a senior student. Jianning, he is my supervisor guiding me the master project, who is the guide leading me to enter the new domain of stellar physics—asteroseimology. I must thank our team, PS2E, which consists of more than twenty researchers and about ii ten students, for their embrace. We have four defenses this year, Mathieu Gaurat, Giovanni Mirouh, Morgan Deal and me. It is a great pleasure to work with you and be your friend. I owe you thanks for many helps and, especially, for being a translator. Rohit Kumar came to our lab not too long, while, you help me quite a lot to prepare for the defense. Thank you very much. I would like to thank our great young researchers, Sebastien Deheuvels, for whom organize the Journal Club and Workshop, and especially for the happy hour party, Clément Baruteau, for the vivid memory of the red wine from a chateau in the dark, Jérôme Ballot and Pascal Petit, for their charge of our group working well, ..., they are many. I also grateful to thank the excellent senior researchers, François Lignières, the director of PE2E team, for his discussion about the guideline to be a qualified student in the team, Michel Rieutord, for his discussion of physics and life, ..., they are many. I also thank the administrative staffs in the lab and the doctoral school. They are Emillie Dupin and Josette Garcia, the secretary of the IRAP, Isabelle Moro, the accountant of the PS2E team, Martin Giard and Philippe Louarn, the previous and current director of the IRAP, Marie-Claude Cathala, the secretary of the doctoral school, Genevieve Soucail, the director of the doctoral school... I would like to thank the China Government for providing the fund to support me living and study in France. Without it, I cannot pursue my study in Université de Toulouse and conduct my research in the lab IRAP (CNRS). I would also like to thank the funds from the Programme National de Physique Stellaire (PNPS, CNRS/INSU, France) and the Centre National d’Études Spatiales (CNES, France) that support me to attend many international conferences. Then it makes me learn many researchers in white dwarf stars and hot subdwarf stars possible. Gilles Fontaine is a kind of such people whom I first met in a white dwarf meeting even I heard his name before. Gille is very knowledgable in many research aspects, and more importantly, a gracious friend, for whom I thank the encouraging me to persist my research with confidence. I cannot image that there is no friend for one living in an exotic country. I owe much from my dear friends, most of them are also Ph.d students in Toulouse. I share joys and sorrows with them, go skiing and hiking with them, have parties and communicate many different living skills with them.... They are Chen couple, Chen Chunxian, Gao Congzhang, Ke Diandian, Leng Faqiang, Lin Zifeng, Tian Feng, Wang Renjie, Zhao Xuefei... and many. Finally, I am very grateful to my family, my father and mother, my younger brother and sister, for their supporting and understanding me that let me purchase my doctor degree in a foreign environment and culture, six or seven hours time lagging behind, many thousands miles away from them, almost across the entire continent, a long-haul trip of one transfer flight and one corresponding train to home. iii Résumé Les interactions non linéaires entre modes de pulsation, induisant des modulations d’ampli- tude et de fréquence, sont difficiles à mettre en évidence avec les télescopes au sol en raison des temps caractéristiques en jeu, de l’ordre de la semaine, du mois, ou même de l’année. L’avène- ment des télescopes spatiaux comme KEPLER (opéré par la NASA) a considérablement changé la donne en apportant de nouvelles données pour ce domaine de recherche. Dans cette thèse, nous analysons les données photométriques obtenues avec KEPLER pour 24 étoiles compactes pulsantes, incluant 18 étoiles sous-naines de type B (sdB) et 6 naines blanches. Nous établissons que les modulations d’amplitude et de fréquence des modes d’oscillation sont un phénomène courant dans ces étoiles. Nous étudions en particulier deux étoiles : KIC 0862602, une naine blanche pulsante de type DB, et KIC 10139564, une étoile sdB variable à courtes périodes. KIC 0862602 et KIC 10139564 ont été observées sans interruption par KEPLER en cadence ra- pide pendant deux années pour la première et plus de trois ans pour la seconde. En analysant en détail ces données photométriques de très haute précision, nous mettons en évidence différents types de comportements affectant les composantes de triplets induits par la rotation stellaire. Les fréquences et amplitudes de ces modes montrent des variations soi périodiques soi irrégu- lières, ou demeurent constantes. Ces comportements peuvent être connectés à ceux prédits par les équations d’amplitude dans le cas de couplages non linéaires résonants entre modes, en par- ticulier pour les temps caractéristiques des modulations. De plus, nous montrons que les modes en résonance constituant les triplets peuvent également interagir avec des modes extérieurs par le biais d’autres formes de résonances telle que la résonance à trois modes ν0 ∼ ν1 + ν2, une situation qui n’est pas prise en compte dans le cadre théorique existant.
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