Study of Sun-like G Stars and Their Exoplanets Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy by Mr. SHASHANKA R. GURUMATH May, 2019 ABSTRACT By employing exoplanetary physical and orbital characteristics, aim of this study is to understand the genesis, dynamics, chemical abundance and magnetic field structure of Sun-like G stars and relationship with their planets. With reasonable constraints on selection of exoplanetary physical characteristics, and by making corrections for stellar rate of mass loss, a power law relationship between initial stellar mass and their exo- planetary mass is obtained that suggests massive stars harbor massive planets. Such a power law relationship is exploited to estimate the initial mass (1.060±0.006) M of the Sun for possible solution of “Faint young Sun paradox” which indeed indicates slightly higher mass compared to present mass. Another unsolved puzzle of solar system is angular momentum problem, viz., compare to Sun most of the angular momentum is concentrated in the solar system planets. By analyzing the exoplanetary data, this study shows that orbital angular momentum of Solar system planets is higher compared to orbital angular momentum of exoplanets. This study also supports the results of Nice and Grand Tack models that propose the idea of outward migration of Jovian planets during early history of Solar system formation. Furthermore, we have examined the influence of stellar metallicity on the host stars mass and exoplanetary physical and orbital characteristics that shows a non-linear relationship. Another important result is most of the planets in single planetary stellar systems are captured from the space and/or inward migration of planets might have played a dominant role in the final architecture of single planetary stellar systems. Finally, with the host star chromospheric activity as a magnetic field proxy, following problems are investigated. At the present epoch, influence of planetary mass on the host star’s magnetic activity is examined and it is found that host star’s magnetic activity is independent of any planetary mass present in the vicinity of the host star. At the early epoch of planetary formation, the role of large- scale magnetic field on the planetary formation is examined which suggests that strong magnetic field inhibits more concentration of planetary mass in the protoplanetary disk. Keywords: Exoplanets, Sun, Solar system, stars:evolution. i ACKNOWLEDGEMENT With immense pleasure and deep sense of gratitude, I wish to express my sin- cere thanks to my supervisors Dr. V. Ramasubramanian, Professor, Department of Physics, School of Advanced Sciences (SAS), Vellore Institute of Technology, Vellore and, Dr. K. M. Hiremath, Professor, Indian Institute of Astrophysics (IIA), Bengaluru, without their motivation and continuous encouragement, this research would not have been successfully completed. I am grateful to the Chancellor of Vellore Institute of Technology, Dr. G. Viswanathan, the Vice Presidents, the Vice Chancellor for providing me infrastruc- tural facilities to carry out research in the Vellore Institute of Technology. I express my sincere thanks to Dr. R. Vijayaraghavan, Dean, School of Ad- vanced Sciences (SAS), Vellore Institute of Technology, Dr. Sathya Swaroop N. R., HOD, Department of Physics, SAS, Vellore Institute of Technology, and Dr. Anu Radha C., Associate Professor, SAS, Vellore Institute of Technology for their kind words of support and constant encouragement. I am thankful to Director, Indian Institute of Astrophysics (IIA), Bengaluru, and Board of Graduate Studies (BGS), IIA, Bengaluru for providing short-term in- ternships, allowing me to use library and computer facilities during my visits at Indian Institute of Astrophysics. I also thankful to Dr. Manjunath Hegde, IIA, for helping me in all aspects during initial days of my PhD. I would like to extend the gratitude towards my doctoral committee members Dr. S. B. Gudennavar, Christ University, Bengaluru and Dr. Lovely M. R., Sreekr- ishna College, Guruvayur, for their advice, encouragement, suggestions and insightful comments during the academic meetings. I would like to acknowledge the support rendered by my friends Sindhu N. for useful discussions. Dr. Laurel, Dr. R. Arunkumar, Pavan, Nandan, Boopathi, Sadashiv and Dr. Manimaran for their constant support in academic and also during four years stay at Vellore. In addition, the colleagues, friends in CRC lab, Vellore, and all other friends and roommates at Bengaluru, without them there wouldn’t be fun in ii TABLE OF CONTENTS ABSTRACT .................................... i ACKNOWLEDGEMENT ............................. ii LIST OF FIGURES ................................ ix LIST OF TABLES . xviii LIST OF TERMS AND ABBREVIATIONS . xix 1 Introduction 1 1.1 Solar System . 2 1.2 The Sun . 2 1.2.1 Internal Structure of The Sun . 3 1.2.2 Atmosphere of The Sun . 6 1.2.3 Solar Dynamics . 8 1.2.4 Chemical Abundances of The Sun . 9 1.2.5 Solar Cycle and Activity Phenomena . 11 1.2.6 Helioseismology . 13 1.3 Physical And Orbital Properties of Solar System Objects . 15 1.3.1 Terrestrial Planets . 16 1.3.2 Jovian Planets . 23 1.3.3 Other Objects . 27 1.4 Different Theories on Genesis of Solar System Formation . 30 1.4.1 The Laplace Nebular Hypothesis . 30 1.4.2 The Roche Model . 31 1.4.3 The Chamberlin and Moulton Planetesimal Theory . 32 1.4.4 The Jeans Tidal Theory . 33 1.4.5 The Solar Nebula Theory . 34 iv 1.4.6 Recent Important Models . 35 2 Exoplanets 37 2.1 Brief History of Detection of Planets Outside the Solar System . 38 2.2 Importance of Studying the Exoplanets . 39 2.3 Different Detection Methods And Characterization of Exoplanets . 41 2.3.1 Radial Velocity (RV) Method . 41 2.3.2 Transit Method . 45 2.3.3 Microlensing Method . 51 2.3.4 Direct Imaging Method . 54 2.4 Challenges of the Exoplanetary Systems . 56 2.4.1 Observational Challenges . 56 2.4.2 Theoretical Challenges . 58 3 Missions for Detection of Exoplanets 59 3.1 Ground Based Observations . 59 3.1.1 High Accuracy Radial Velocity Planet Searcher (HARPS) . 59 3.1.2 High Accuracy Radial Velocity Planet Searcher for Northern hemi- sphere (HARPS-N) . 60 3.1.3 Hanle Echelle Spectrograph - HESP . 61 3.1.4 SuperWASP . 61 3.1.5 HATNet Project . 62 3.2 Space Based Observations . 63 3.2.1 CoRoT Space Telescope . 63 3.2.2 Kepler Space Telescope and K2 . 63 3.2.3 Astrosat . 65 3.3 Future Space and Ground Based Probes for Detection of Exoplanets . 67 3.3.1 James Webb Space Telescope . 67 3.3.2 CHEOPS Mission . 68 3.3.3 TESS - Transiting Exoplanet Survey Satellite . 70 3.3.4 Thirty Meter Telescope - TMT . 70 v 3.3.5 PLAnetary Transits and Oscillations of stars - PLATO . 72 4 Mass Relationship Between Sun-like Stars and Their Exoplanets 73 4.1 Estimation of Mass of Stars . 74 4.1.1 From Binary Stars . 74 4.1.2 Luminosity-Mass Relationship . 77 4.1.3 Asteroseismic Method . 77 4.2 Estimation of Age of a Star . 78 4.3 Different Techniques to Measure the Mass Loss From the Stars . 79 4.4 Motivation . 81 4.5 Data and Analysis . 82 4.6 Estimation of Mass Loss From the Host Stars . 83 4.6.1 Rate of Mass Loss Estimated From the Host Stars That Have Ex- oplanets . 84 4.6.2 Rate of Mass Loss Estimated From the Observations of Stars . 86 4.6.3 Computation of Initial Stellar Mass . 87 4.7 Results and Conclusion . 88 4.7.1 Estimation of Initial Mass of The Sun . 89 4.7.2 Estimation of initial planetary mass in the vicinity of Sun . 91 4.7.3 Conclusions . 92 5 Angular Momentum of Sun-like G Stars and Their Exoplanets 94 5.1 Estimation of Stellar Rotation . 94 5.1.1 Spectroscopic method . 94 5.1.2 Photometric Method . 95 5.2 Angular Momentum Problem of the Solar System . 96 5.3 Angular Momentum of the Host Stars That Have Exoplanets . 97 5.4 Motivation . 97 5.5 Data And Analysis . 98 5.6 Results And Conclusions . 100 5.6.1 Orbital Angular Momentum of Exoplanets . 100 vi 5.6.2 Spin Angular Momentum of Confirmed Planetary Host Stars . 102 5.6.3 Total Angular Momentum of The Confirmed Planetary Systems . 110 5.6.4 Clues for the Low Mass Planets and Missing Mass in the Vicinity of Sun . 115 5.7 Conclusions . 118 6 Metallicity of Sun-like G Stars and Their Exoplanets 120 6.1 Metallicity of Host Stars . 120 6.2 Motivation . 121 6.3 Data and Analysis . 123 6.4 Results and Discussion . 124 6.4.1 Stellar Mass Versus Metallicity . 125 6.4.2 Dependence of metallicity with the planetary physical properties . 130 6.4.3 Orbital Distances of Exoplanets Versus Stellar Metallicity . 137 6.5 Conclusions . 138 7 Magnetic Field Structure of Sun-Like G Stars and Their Exoplanets 140 7.1 Zeeman Effect . 141 7.2 Polarization . 142 7.3 Zeeman-Doppler Imaging . 143 7.4 Chromospheric Activty . 144 7.5 Motivation . 145 7.6 Data And Analysis . 148 7.7 Results and Discussion . 149 7.7.1 Magnetic Activity at the Present Epoch . 151 7.7.2 Variation of Chromopheric Activity With Planetary Mass . 154 7.7.3 Magnetic Field Structure in the Early Epoch . 155 7.8 Conclusions . 157 8 Summary of Thesis and Future Prospects 159 8.1 Summary of The Thesis . 159 8.2 Future Prospects . 164 vii REFERENCES ...............................167 LIST OF PUBLICATIONS . 189 viii LIST OF FIGURES 1.1 Illustrates the Radial Variation of Temperature, Pressure, Density and Luminosity in the Interior of the Sun From Its Center to Surface. the X-Axis Represents the Fraction of Radius in Terms of Sun’s Radius and Y-Axis Represents Different Physical Parameters.