Interferometry as a tool to calibrate evolutionary tracks

Cusano, Felice GND

Up to now, the only way to determine the masses of single stars at different ages was to use the evolutionary tracks. Depending on the authors the evolutionary tracks for stars of the same masses are different. It is therefore important to test which models better predict the observations. In this PhD-thesis I present methods to determine physical parameters of young and evolved stars, combining spectroscopy with optical interferometry. The first part of the thesis discuss PMS stars, while the second part giant stars. Combining optical interferometry with spectroscopy it is possible to measure the dynamical masses of stars in binary systems. In the case of PMS stars I performed a spectroscopic survey to search for young binaries. The result was the collection of a sample of 13 young spectroscopic binary (SB). For these, I determined the orbital parameters and in two cases the mass ratios. For HD113449 I obtained interferometric observations with AMBER@VLTI. Combing these data with the spectroscopy, I determined the masses of the components of HD113449. Comparing these mass values and the mass ratios of the two SBs with different set of evolutionary tracks, I found that the Baraffe et al. (1998) tracks fit the observations best. In the case of the test of evolutionary tracks of giant stars, I measured the diameters of 30 giant stars using AMBER@VLTI and the CHARA array. A test was done comparing the diameters estimated from different set of evolutionary tracks with the interferometrically measured ones. This test showed that the Salasnich et al. (2000) models are the ones best fitting the observations. In the case of HD170693, I also obtained time series observations with the high resolution spectrograph at the TLS Tautenburg, deriving the oscillation frequencies from the measured radial velocities. Combining these informations with the interferometric diameter, I obtained the mass of this giant, which is in good agreement with the one from the models.


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