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Review of Detecting of the Extrasolar Planets with Transit Method

Eskandari, Esmaeel | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40914 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Rahvar, Sohrab
  7. Abstract:
  8. One of the beautiful branches of Astrophysics is studing of binary systems and specially eclipsing binary sytems which is included transiting eclipsing extrasolar planets. Detecting of extrasolar planets with transit method is based on which a planet orbits around a star and when its orbit alignment is such that planet along our line of sight across disk of star, it causes eclipse of star and a drop in star’s brightness and from this we can find the existence of a planet. In analysis of observational light curve (obtained from data acquisition with photometry method) a synthetic light curve, constructed from a theoretical model which is based on transit, planet and star geometry, is fitted on observational light curve by a programming code. In design of this model we also consider different effects such as decrease of the star brightness from center to limb (limb darkening), oblateness of star’s shape (because of its rotation) and its influence on local surface gravity and consequently increase of star brightness from its equator to pole (gravity brightening), the existence of a source of third light on background or foreground of picture of star and planet (third light), brightening of that side of planet which is in the face of the star because of reflection of incident flux from star (reflection effect). With this fitting we can obtain the geometrical parameters of the star and planet. Then we get radial velocity amplitude of the star from results of radial-velocity measurements of the star and with another extra constraint (radial velocity amplitude of the planet) and with the help of obtained parameters from light curve analysis we compute star’s mass and radius. We also use effective temperature and metallicity of the star (obtained from elsewhere). With the star’s mass and its metallicity as inputs of a theoretical model predictor of effective temperature, radius and structure of the star (theoretical stellar revolution model) which implemented in a programming code, we can obtain star’s effective temperature and radius. These effective temperature and radius is fitted on measured effective temperature and calculated radius in an optimizing process with change of extra constraint (radial velocity amplitude of the planet). Finally with these optimized radial velocity amplitude of the planet and star and obtained geometrical parameters from light curve analysis, we obtain physical properties of star and planet such as their masses, surface gravities and densities and also semi major axis and their absolute radii
  9. Keywords:
  10. Modeling ; Extrasolar Planets ; Transit Method ; Photometry

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