Peculiar Variations of White Dwarf Pulsation Frequencies ... PECULIAR VARIATIONS OF WHITE DWARF PULSATION

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  • PECULIAR VARIATIONS OF WHITE DWARF PULSATION

    FREQUENCIES AND MAESTRO

    by

    James Ruland Dalessio

    A dissertation submitted to the Faculty of the University of Delaware in partialfulfillment of the requirements for the degree of Doctor of Philosophy in Physics

    Spring 2013

    c 2013 James Ruland DalessioAll Rights Reserved

  • PECULIAR VARIATIONS OF WHITE DWARF PULSATION

    FREQUENCIES AND MAESTRO

    by

    James Ruland Dalessio

    Approved:Edmund R. Novak, Ph.D.Chair of the Department of Physics and Astronomy

    Approved:George H. Watson, Ph.D.Dean of the College of Arts and Sciences

    Approved:James G. Richards, Ph.D.Vice Provost for Graduate and Professional Education

  • I certify that I have read this dissertation and that in my opinion it meets theacademic and professional standard required by the University as a dissertationfor the degree of Doctor of Philosophy.

    Signed:Henry L. Shipman, Ph.D.Professor in charge of dissertation

    I certify that I have read this dissertation and that in my opinion it meets theacademic and professional standard required by the University as a dissertationfor the degree of Doctor of Philosophy.

    Signed:Judith L. Provencal, Ph.D.Member of dissertation committee

    I certify that I have read this dissertation and that in my opinion it meets theacademic and professional standard required by the University as a dissertationfor the degree of Doctor of Philosophy.

    Signed:James MacDonald, Ph.D.Member of dissertation committee

    I certify that I have read this dissertation and that in my opinion it meets theacademic and professional standard required by the University as a dissertationfor the degree of Doctor of Philosophy.

    Signed:Donald E. Winget, Ph.D.Member of dissertation committee

    I certify that I have read this dissertation and that in my opinion it meets theacademic and professional standard required by the University as a dissertationfor the degree of Doctor of Philosophy.

    Signed:Stephen M. Barr, Ph.D.Member of dissertation committee

  • ACKNOWLEDGEMENTS

    Firstly, I thank Judi Provencal, who has put up with my antics for over 6

    years. For all practical purposes, Judi served as my research advisor throughout my

    graduate career. Judi found the perfect balance of guidance and freedom for me to

    grow throughout graduate school and weve had a lot fun along the way. Id also like

    to thank Harry Shipman, who served as my official advisor. Harry was always there to

    mentor me in both my teaching and my research.

    The data used for this research would not have been obtained if it werent for

    the diligent work of Denis Sullivan, Fergal Mullally, and JJ Hermes. To them, I am

    forever indebted for the many hours they spent observing and reducing data. Id also

    like to thank Roy stensen for his work searching for a DB in the Kepler field and

    spearheading Kepler observations of KIC 8626021.

    Whenever I had a tough theoretical question, Mike Montgomery was always

    happy to help whether it was through email or Skype. Fergal Mullally offered extremely

    helpful suggestions and discussion as referee of my first major publication. I learned a

    lot about computers from Staszek Zola, and we had a lot of laughs. I also enjoyed time

    spent with members of the WET team, including Susan Thompson, Kepler, Agnes

    Kim, Denis Sullivan, Don Winget, and the many many others.

    In the early years of graduate school, I spent many hours studying with fellow

    graduate students including Josh Wickman, Dana Saxson, and Mary Oksala. Thanks

    to you folks for keeping me sane in the first few years. The Final Countdown will

    forever remind me of the qualifiers. I also met many graduate students in my field

    at other institutions. I always look forward to seeing JJ Hermes, Ross Falcon, Brad

    Barlow, Paul Chote, Bart Dunlap, and others. I have greatly enjoyed our conversations

    over the last few years.

    iv

  • Ive had the opportunity to TA, instruct several courses, and develop lab cur-

    riculum. I enjoyed TAing for Peter Georgopolus and working with Almas Khan, Abby

    Pillitteri, and Mary Oksala along the way.

    I thank Dermott Mullan and those at the Delaware Space Grant Consortium

    for two full years of funding. I also thank Mount Cuba/Crystal Trust for funding me

    for the first few semesters.

    Without some physical activity I would have gone (completely) crazy. Special

    thanks to Mark Poindexter and the folks at Wilbur for organizing our weekly basketball

    games and to Joe Wiseman, Lori Marinucci, and the New Castle county softball crew

    for organizing the many years of softball. Ive recently also enjoyed playing softball

    (and post-game activities) with the Honey Badgers, despite our incredibly terrible

    performance on the field.

    In last few years, John Meyer and I have become good friends and have had

    many epic physics and philosophy conversations over lunch. Ive also enjoyed our mini

    video game marathons. Its been a blast and I look forward to starting a software

    company with John in the very near future.

    Thanks to my mom, my in-laws Art and Diane, and my sister in-law Amanda,

    who all took turns taking care of Aria while I worked on the final stretch of my Ph.D.

    Extra thanks to my mom, who has always supported me, even in those years when

    I was especially difficult. A special thanks to my step-father for his helpful advice

    and diligent proof-reading, and for keeping me in touch with mainstream astronomy.

    My father did not get to see me finish graduate school, but no doubt he would be very

    proud.

    Lastly and most of all, I thank my wife, who is as patient as she is beautiful.

    During the course of graduate school Lindsay and I were engaged, married, and wel-

    comed our first child. Lindsay has supported me during every step of this long process

    and I wouldnt have made it without her.

    v

  • To my wife

    vi

  • TABLE OF CONTENTS

    LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xLIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii

    PART I PECULIAR VARIATIONS OF WHITE DWARFPULSATION FREQUENCIES . . . . . . . . . . . . . . . . . . . . . . . . 1

    Chapter

    1 BACKGROUND, FORMALISM, AND METHODOLOGY . . . . 2

    1.1 White Dwarf Asteroseismology . . . . . . . . . . . . . . . . . . . . . . 2

    1.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.1.2 Cooling Processes . . . . . . . . . . . . . . . . . . . . . . . . . 51.1.3 Rotation and Magnetic Fields . . . . . . . . . . . . . . . . . . 61.1.4 Pulsation Timing Based Planet Detection . . . . . . . . . . . 71.1.5 Combination and Harmonic Modes . . . . . . . . . . . . . . . 8

    1.2 Miscellaneous Considerations . . . . . . . . . . . . . . . . . . . . . . 9

    1.2.1 Creating a Lightcurve . . . . . . . . . . . . . . . . . . . . . . 91.2.2 Linearizing a Non-Linear Model . . . . . . . . . . . . . . . . . 10

    1.3 Fourier Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

    1.3.1 The Fourier Transform . . . . . . . . . . . . . . . . . . . . . . 10

    1.3.1.1 Definition . . . . . . . . . . . . . . . . . . . . . . . . 10

    vii

  • 1.3.1.2 Properties . . . . . . . . . . . . . . . . . . . . . . . . 11

    1.3.2 Identifying Sinusoidal Variations in a Lightcurve . . . . . . . . 121.3.3 Frequency Bootstrapping . . . . . . . . . . . . . . . . . . . . . 13

    1.4 The O C Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

    1.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141.4.2 Mathematical Description . . . . . . . . . . . . . . . . . . . . 151.4.3 Causes of Perturbations to O C . . . . . . . . . . . . . . . . 18

    1.4.3.1 Error in the Frequency . . . . . . . . . . . . . . . . . 181.4.3.2 Movement of the Source . . . . . . . . . . . . . . . . 181.4.3.3 Intrinsic Frequency Perturbations . . . . . . . . . . . 211.4.3.4 Indistinguishable Processes . . . . . . . . . . . . . . 21

    1.4.4 Calculating O C . . . . . . . . . . . . . . . . . . . . . . . . 221.4.5 Phase Ambiguity . . . . . . . . . . . . . . . . . . . . . . . . . 23

    2 EC 20058-5234 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

    2.1 Observations and Data Preparation . . . . . . . . . . . . . . . . . . . 252.2 Fourier Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272.3 O C Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342.4 Amplitude Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . 46

    3 KIC 8626021 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

    3.1 Observations and Data Preparation . . . . . . . . . . . . . . . . . . . 583.2 Fourier Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 613.3 O C Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 613.4 Amplitude Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . 83

    4 GD 66 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

    4.1 Observations and Data Preparation . . . . . . . . . . . . . . . . . . . 1044.2 Fourier Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1064.3 O C Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1154.4 Amplitude Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . 148

    5 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

    5.