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تسجيل مستخدم جديدA PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- IV. Candidate exoplanets around stars in open clusters: frequency and age-planetary radius distribution
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The knowledge of the ages of stars hosting exoplanets allows us to obtain an overview on the evolution of exoplanets and understand the mechanisms affecting their life. The measurement of the ages of stars in the Galaxy is usually affected by large uncertainties. An exception are the stellar clusters: for their coeval members, born from the same molecular cloud, ages can be measured with extreme accuracy. In this context, the project PATHOS is providing candidate exoplanets orbiting members of stellar clusters and associations through the analysis of high-precision light curves obtained with cutting-edge tools. In this work, we exploited the data collected during the second year of the TESS mission. We extracted, analysed, and modelled the light curves of $sim 90000$ stars in open clusters located in the northern ecliptic hemisphere in order to find candidate exoplanets. We measured the frequencies of candidate exoplanets in open clusters for different orbital periods and planetary radii, taking into account the detection efficiency of our pipeline and the false positive probabilities of our candidates. We analysed the Age--$R_{rm P}$ distribution of candidate and confirmed exoplanets with periods $<100$ days and well constrained ages. While no peculiar trends are observed for Jupiter-size and (super-)Earth-size planets, we found that objects with $4,R_{rm Earth} lesssim R_{rm P} lesssim 13,R_{rm Earth}$ are concentrated at ages $lesssim 200$ Myr; different scenarios (atmospheric losses, migration, etc.) are considered to explain the observed age-$R_{rm P}$ distribution.
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The TESS mission will survey ~85 % of the sky, giving us the opportunity of extracting high-precision light curves of millions of stars, including stellar cluster members. In this work, we present our project A PSF-based Approach to TESS High quality
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The study is devoted to search for flare stars among confirmed members of Galactic open clusters using high-cadence photometry from {it TESS} mission. We analyzed 957 high-cadence light curves of members from 136 open clusters. As a result, 56 flare
stars were found, among them 8 hot B-A type objects. Of all flares, 63% were detected in a sample of cool stars ($T_{rm eff}<5000$~K), and 29% -- in stars of spectral type G, while 23% in K-type stars and approximately 34% of all detected flares are in M-type stars. Using the FLATWRM (FLAre deTection With Ransac Method) flare finding algorithm, we estimated parameters of flares and rotation period of detected flare stars. The flare with the largest amplitude appears on the M3 type EQ,Cha star. Statistical analysis did not reveal any direct correlation between ages, rotation periods and flaring activity.
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is work is to investigate the relations of different chemical abundance ratios vs age traced by red clump (RC) stars in OCs. Methods: We analyze a large sample of 209 reliable members in 47 OCs with available high-resolution spectroscopy. We applied a differential line-by-line analysis to provide a comprehensive chemical study of 25 chemical species. This sample is among the largest samples of OCs homogeneously characterized in terms of atmospheric parameters, detailed chemistry, and ages. Results: In our metallicity range (-0.2<[M/H]<+0.2) we find that while most Fe-peak and alpha elements have flat dependence with age, the s-process elements show decreasing trends with increasing age with a remarkable knee at 1 Gyr. For Ba, Ce, Y, Mo and Zr we find a plateau at young ages (< 1 Gyr). We investigate the relations of all possible combinations among the computed chemical species with age. We find 19 combinations with significant slopes, including [Y/Mg] and [Y/Al]. The ratio [Ba/alpha] is the one with the most significant correlations found. Conclusions: We find that the [Y/Mg] relation found in the literature using Solar twins is compatible with the one found here in the Solar neighbourhood. The age-abundance relations show larger scatter for clusters at large distances (d>1 kpc) than for the Solar neighbourhood, particularly in the outer disk. We conclude that these relations need to be understood also in terms of the complexity of the chemical space introduced by the Galactic dynamics, on top of pure nucleosynthetic arguments, especially out of the local bubble.
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