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12,660 Spotted Stars toward the OGLE Galactic Bulge Fields

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dc.abstract.enWe present the discovery and statistical analysis of 12,660 spotted variable stars toward and inside the Galactic bulge from the Optical Gravitational Lensing Experiment (OGLE) data that are over two decades long. We devise a new method of dereddening of individual stars toward the Galactic bulge where strong and highly nonuniform extinction is present. In effect, 11,812 stars were classified as giants and 848 as dwarfs. Well-defined correlations among the luminosity, variability amplitude, and rotation period were found for the giants. Rapidly rotating dwarfs with periods P ≤ 2 days show I-band amplitudes <0.2 mag, which is substantially less than the amplitudes of up to 0.8 mag observed in giants and slowly rotating dwarfs. We also notice that amplitudes of stars brighter than I <SUB>0</SUB> ≈ 16 mag do not exceed 0.3-0.4 mag. We divide the stars into three groups characterized by correlation between light and color variations. The positive correlation is characteristic for stars that are cooler when fainter, which results from the variable coverage of the stellar surface with spots similar to the sunspots. The variability of stars that are cooler when brighter (negative correlation) can be characterized by chemical spots with an overabundance of heavy elements inside and a variable line-blanketing effect, which is observed in chemically peculiar stars. The null correlation may result from a very high level of the magnetic activity with rapidly variable magnetic fields. This division is readily visible on the color-magnitude diagram (CMD), which suggests that it may depend on the radius of the stars. We detect 79 flaring objects and discuss briefly their properties. Among others, we find that relative brightening during flares is correlated with brightness amplitude.
dc.affiliationUniwersytet Warszawski
dc.contributor.authorIwanek, Patryk
dc.contributor.authorSoszyński, Igor
dc.contributor.authorSkowron, Jan
dc.contributor.authorUdalski, Andrzej
dc.contributor.authorStępień, Kazimierz
dc.contributor.authorKozłowski, Szymon
dc.contributor.authorMróz, Przemysław
dc.contributor.authorPoleski, Radosław
dc.contributor.authorSkowron, Dorota
dc.contributor.authorSzymański, Michał
dc.contributor.authorPietrukowicz, Paweł
dc.contributor.authorUlaczyk, Krzysztof
dc.contributor.authorWyrzykowski, Łukasz
dc.contributor.authorKruszyńska, Katarzyna
dc.contributor.authorRybicki, Krzysztof
dc.date.accessioned2024-01-24T15:35:03Z
dc.date.available2024-01-24T15:35:03Z
dc.date.copyright2019-03-13
dc.date.issued2019
dc.description.accesstimeBEFORE_PUBLICATION
dc.description.financeNie dotyczy
dc.description.number2
dc.description.versionORIGINAL_AUTHOR
dc.description.volume879
dc.identifier.doi10.3847/1538-4357/AB23F6
dc.identifier.issn0004-637X
dc.identifier.urihttps://repozytorium.uw.edu.pl//handle/item/100006
dc.identifier.weblinkhttp://adsabs.harvard.edu/abs/2019ApJ...879..114I
dc.languageeng
dc.pbn.affiliationastronomy
dc.relation.ispartofAstrophysical Journal
dc.relation.pages114
dc.rightsOther
dc.sciencecloudnosend
dc.title12,660 Spotted Stars toward the OGLE Galactic Bulge Fields
dc.typeJournalArticle
dspace.entity.typePublication