Aleksander Wolszczan

Observing the PTPS sample of evolved exoplanet host candidates using the NPOI

We plan to measure the angular diameters of a sample of Penn State-Torun Planet Search (PTPS) giant exoplanet host star candidates using the Navy Precision Optical Interferometer. The radii of evolved giant stars obtained using spectroscopy are usually ill-defined because of the method’s indirect nature and evolutionary model dependency. The star’s radius is a critical parameter used to calculate luminosity and mass, which are often not well known for giant stars. Therefore, this problem also affects the orbital period, mass, and surface temperature of the planet. Our interferometric observations will significantly decrease the errors for these parameters. We present preliminary results from NPOI observations of six stars in the PTPS sample.

PTPS Candidate Exoplanet Host Star Radii Determination with CHARA Array

We propose to measure the radii of the Penn State - Torun Planet Search (PTPS) exoplanet host star candidates using the CHARA Array. Stellar radii estimated from spectroscopic analysis are usually inaccurate due to indirect nature of the method and strong evolutionary model dependency. Also the so-called degeneracy of stellar evolutionary tracks due to convergence of many tracks in the giant branch decreases the precision of such estimates. However, the radius of a star is a critical parameter for the calculation of stellar luminosity and mass, which are often not well known especially for giants. With well determined effective temperature (from spectroscopy) and radius the luminosity may be calculated precisely. In turn also stellar mass may be estimated much more precisely. Therefore, direct radii measurements increase precision in the determination of planetary candidates masses and the surface temperatures of the planets.

The Pennsylvania—Toruń Planet Search: Target Characteristics and Recent Results

More than 450 stars hosting planets are known today but only approximately 30 planetary systems were discovered around stars beyond the Main Sequence. The Pennsylvania‐Torun Planet Search, putting an emphasis on extending studies of planetary system formation and evolution to intermediate‐mass stars, is oriented towards the discoveries of substellar‐mass companions to a large sample of evolved stars using high‐precision radial velocity technique. We present the recent status of our survey and detailed characteristic for ∼350 late type giant stars, i.e. the new results of radial velocity analysis and stellar fundamental parameters obtained with extensive spec‐troscopic method. Moreover, in the future we will make an attempt to perform the statistical study of our sample and searching the correlations between the existence of substellar objects and stellar atmospheric parameters according to previous works which investigated the planetary companion impact on the evolution of the host stars.