Gaia22eor: Symbiotic Star V2756 Sgr Detected in a Deep Eclipse

Abstract

Abstract V2756 Sgr is a long-known S-type symbiotic binary that was recently detected in ∼1 mag eclipse-like fading by the Gaia satellite. This behavior was reported as a Gaia Science Alert under the designation Gaia22eor. V2756 Sgr has not been reported as an eclipsing symbiotic system. In this contribution, we have investigated the recent light curves of this target obtained by Gaia and ASAS-SN survey and supplemented these data by the photometry from the ASAS survey and DASCH archive. In addition, low-resolution BP/RP spectra from Gaia were examined. Based on the presented analysis, we conclude that the observed fading is indeed an eclipse of the hot component of V2756 Sgr by the cool giant. The data also allowed us to refine the orbital period to 725 ± 3 days.