OGLE-ing the Magellanic System: Cepheids in the Bridge

Anna M. Jacyszyn-Dobrzeniecka, I. Soszyński, A. Udalski, M. K. Szymański, D. M. Skowron, J. Skowron, P. Mróz, K. Kruszyńska, P. Iwanek, P. Pietrukowicz, R. Poleski, S. Kozłowski, K. Ulaczyk, K. Rybicki, M. Wrona

Published 2019-04-17Version 1

We present a detailed analysis of Magellanic Bridge Cepheid sample constructed using the OGLE Collection of Variable Stars. Our updated Bridge sample contains 10 classical and 13 anomalous Cepheids. We calculate their individual distances using optical period--Wesenheit relations and construct three-dimensional maps. Classical Cepheids on-sky locations match very well neutral hydrogen and young stars distributions, thus they add to the overall Bridge young population. In three dimensions, eight out of ten classical Cepheids form a bridge-like connection between the Magellanic Clouds. The other two are located slightly farther and may constitute the Counter Bridge. We estimate ages of our Cepheids to be less than 300 Myr for five up to eight out of ten, depending on whether the rotation is included. This is in agreement with a scenario where these stars were formed in-situ after the last encounter of the Magellanic Clouds. Cepheids' proper motions reveal that they are moving away from both Large and Small Magellanic Cloud. Anomalous Cepheids are more spread than classical Cepheids in both two and three dimensions. Even though, they form a rather smooth connection between the Clouds. However, this connection does not seem to be bridge-like, as there are many outliers around both Magellanic Clouds.