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Massive Search for Spot- and Facula-Crossing Events in 1598 Exoplanetary Transit Light Curves

Baluev R. V., Sokov E. N., Sokova I. A., Shaidulin V. Sh., Veselova A. V., Aitov V. N., Mitiani G. Sh., Valeev A. F., Gadelshin D. R., Gutaev A. G., Beskin G. M., Valyavin G. G., Antonyuk K., Barkaoui K., Gillon M., Jehin E., Delrez L., Guðmundsson S., Dale H. A., Fernández-Lajús E., Di Sisto R. P., Bretton M., Wunsche A., Hentunen V.-P., Shadick S., Jongen Y., Kang W., Kim T., Pakštienė E., Qvam J. K. T., Knight C. R., Guerra P., Marchini A., Salvaggio F., Papini R., Evans P., Salisbury M., Garlitz J., Esseiva N., Ogmen Y., Bosch-Cabot P., Selezneva A., Hinse T. C.

Acta Astronomica

2021

Vol. 71, No. 1

25--53

We developed a dedicated statistical test for a massive detection of spot- and facula-crossing anomalies in multiple exoplanetary transit light curves, based on the frequentist p-value thresholding. This test was used to augment our algorithmic pipeline for transit light curves analysis. It was applied to 1598 amateur and professional transit observations of 26 targets being monitored in the EXPANSION project. We detected 109 statistically significant candidate events revealing a roughly 2:1 asymmetry in favor of spots-crossings over faculae-crossings. Although some candidate anomalies likely appear non-physical and originate from systematic errors, such asymmetry between negative and positive events should indicate a physical difference between the frequency of star spots and faculae. Detected spot-crossing events also reveal positive correlation between their amplitude and width, possibly due to spot size correlation. However, the frequency of all detectable crossing events appears just about a few per cent, so they cannot explain excessive transit timing noise observed for several targets.

High-Velocity Moving Groups in the Solar Neighborhood in Gaia DR2

Baluev R. V., Shaidulin V. Sh., Veselova A. V.

Acta Astronomica

2020

Vol. 70, No. 2

141--168

We use an improved wavelet analysis technique to reconstruct the (U,V,W) velocity distribution for ≈250 000 stars from Gaia DR2, located in the solar neighborhood of 200 pc. The 2D wavelet transforms for three bivariate distributions (U,V), (U,W), and (V,W) were investigated. Though most of currently known (low-velocity) stellar moving groups are densely overlapped in these diagrams, our analysis allowed us to detect and disentangle about twenty statistically significant 3D groups of stars with high velocities. Most of them appear to be new discoverirs. We also discuss the issue of correct noise thresholding in the wavelet transform and highlight the importance of using a global rather than local statistic for that. Using of a local significance measure may lead to an overstated statistical confidence for individual patterns due to the effect of multiple testing.