Sobre a natureza da variabilidade fotométrica em estrelas TESS com trânsitos planetários

Abstract

Different space missions are revolutionizing our understanding of stellar variability, revealing a new view of dynamic phenomena associated with stars in different regions of the HR diagram. Furthermore, environments with planet-hosting stars have proved to be complex and primordial laboratories for the understanding of star-planet relationships, where much of the information about this interaction is revealed as particular aspects of the star’s light curve including rotation, pulsation and transient events. Rotation is a parameter that can be characterized by the detection of spots on the surface of the star and plays, in fact, an important role in controlling stellar evolution and in a potential scenario of planetary habitability. In this sense, the study of periodicities in stars with planets, from photometric observations, such as those associated with the KEPLER and TESS missions, opens new perspectives for the study of different stellar properties, including rotation and magnetic activity. In this work, we carried out a search for signatures of photometric variability in the light curves of 2215 TOI (Tess Objects of Interest) stars with planets discovered by the TESS telescope, via planetary transit. For objects with clear photometric modulation, we determined their periodicities by applying the BLS, FFT, Lomb-Scargle and Wavelet techniques. The results of this analysis are described in Canto Martins et al. (2020), where, from the total of 2215 stars, we found 289 TOI with rotation signature, 11 TOI with pulsation signature subdivided into 4 different classes, 318 TOI with ambiguous variability, 1586 TOI with low signal-to-noise ratio and 11 eclipsing binary TOI. We studied the Porb/Prot × Porb distribution of stars with rotation signature and identified a possible synchronicity between the rotational period and the orbit of the innermost planet for some of them. In addition, in this subsample we found 30 stars that present eruption events, a phenomenon of great importance in the study of planetary habitability, as they are events that can impact the development and continuity of biological activity. Likewise, recent studies on pulsating stars have shown that carbon, one of the fundamental elements for the existence of life, may be being released into the interstellar medium through these variables, which makes our subsample of 11 TOI more interesting as they are targets with potential planets. Finally, we made a solid characterization of the evolutionary state of the analyzed stellar sample, from a Color-Magnitude Diagram with data from GAIA, and we identified 1511 stars as probable members of the Main Sequence (MS) and 546 evolved stars, which reveals us that the distribution of our sample is predominantly from MS, including stars with rotation signature.