YSOVAR: Six pre-main-sequence eclipsing binaries in the Orion Nebula Cluster

摘要

Eclipsing binaries (EBs) provide critical laboratories for empiricallytesting predictions of theoretical models of stellar structure and evolution.Pre-main-sequence (PMS) EBs are particularly valuable, both due to their rarityand the highly dynamic nature of PMS evolution, such that a dense grid of PMSEBs is required to properly calibrate theoretical PMS models. Analyzingmulti-epoch, multi-color light curves for 2400 candidateOrion Nebula Cluster(ONC) members from our Warm Spitzer Exploration Science Program YSOVAR, we haveidentified 12 stars whose light curves show eclipse features. Four of these 12EBs are previously known. Supplementing our light curves with follow-up opticaland near-infrared spectroscopy, we establish two of the candidates as likelyfield EBs lying behind the ONC. We confirm the remaining six candidate systems,however, as newly identified ONC PMS EBs. These systems increase the number ofknown PMS EBs by over 50% and include the highest mass (Theta1 Ori E, for whichwe provide a complete set of well-determined parameters including componentmasses of 2.807 and 2.797 solar masses) and longest period (ISOYJ053505.71-052354.1, P \sim 20 days) PMS EBs currently known. In two cases(Theta1 Ori E and ISOY J053526.88-044730.7), enough photometric andspectroscopic data exist to attempt an orbit solution and derive the systemparameters. For the remaining systems, we combine our data with literatureinformation to provide a preliminary characterization sufficient to guidefollow-up investigations of these rare, benchmark systems.