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Two main parameters, which determine the radial velocity semi-amplitude of the host star in a star-planet system, are the planet mass and the orbital period. In order to examine the effect of planet mass on the radial velocity semi-amplitude, we firstly select sensitive data of spectroscopic orbital solutions of 737 systems, given in the database of exoplanet.org. The selected systems are then categorized into 31 groups according to their orbital periods. For each group, an empirical relation between the radial velocity semi amplitude and the planet mass is obtained. In order to check the accuracy of these empirical relations, the measured and expected values of planet masses are compared. [ABSTRACT FROM AUTHOR]

The high-accuracy and high-precision HARPS-N spectrograph has been installed at the italian Telescopio Nazionale Galileo in La Palma approximately two years and a half ago. Eighty nights per year of Guaranteed Time of Observation are mostly dedicated to the radial-velocity (RV) follow up of Kepler small-size planetary candidates to establish their nature and to determine accurately their masses. We report on recent results of this ongoing RV campaign, including the recent characterization of the planetary system Kepler-101. [ABSTRACT FROM AUTHOR]

Radial velocity semi-amplitude of the host star in a star-planet system is affected by four parameters: the orbital period and mass of the planet, mass of the host star, and orbital eccentricity. Statistical distribution of the orbital elements was examined using sensitive data from the spectroscopic orbital solutions of 737 systems given in the Exoplanet Orbit Database and Exoplanet Data Explorer (exoplanet.org). The orbital element distribution of the exoplanets was plotted in separate diagrams to highlight the basic features of the host star and planet in star-planet systems. [ABSTRACT FROM AUTHOR]

The transit light curve of a transiting exoplanet offers us an opportunity to measure the fractional radius, semi-major axis and orbital inclination of the star-planet system. Precision of those parameters is strongly affected by limb darkening of the host star. In this study, we examine the limb darkening effect on the transit light curves of HAT-P-32b. The transit light curves of HAT-P-32b were observed on three nights at TUBITAK National Observatory with a 100-cm aperture telescope in Bessel R and V filters. The light curves were solved using jktebop code. Linear, square root, logarithmic and quadratic limb darkening laws were taken into account during the analysis. The derived limb darkening coefficients from our observations were then compared with theoretical values given in the literature. We conclude that more sensitive data, such as space based photometric observations, are needed in order to determine the limb darkening coefficients accurately. [ABSTRACT FROM AUTHOR]