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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.

Photometric Observations of LO Peg in 2014-2015

Savanov I. S., Puzin V. I., Dmitrienko E. S., Karpov S. V., Beskin G. M., Biryukov A. V., Bondar S. F., Ivanov E. A., Katkova E. V., Orekhova N., Perkov A. V., Sasyuk V. V., Romanyuk I. I., Semenko E. A., Kudryavtsev D., Karmakar S., Pandey J. C., Pandey S. B., Joshi S., Misra K.

Acta Astronomica

2016

Vol. 66, No. 3

381--390

We performed new observations of an ultra-fast rotator of the spectral class K - the LO Peg star - in SAO RAS in 2014 and in Zvenigorod Observatory of INASAN in 2015. The light curves were used to build the maps of temperature inhomogeneities on the LO Peg surface in order to determine the longitudes corresponding to the location of active regions. The obtained measurements suggest the ongoing evolution of movements of active regions and probably the cyclic character of such movements. According to our estimations, the area of the star surface covered with spots decreases and by now it reached 14% of the total visible area of its surface. New observations of the star in V filter allowed us to specify LO Peg long-term variability cycles. Based on spectropolarimetric observations of LO Peg the null result for measurements of mean longitudinal component of magnetic field is obtained.