YSOVAR

2011 • 9 sayfa • EN

Yazan Maria Morales-Calderón, John Richard Stauffer, Lynne Anne Hillenbrand, Robert Allen Gutermuth, Inseok Song, Luisa M. Rebull, Peter Paul Plavchan, John Michael Carpenter, Barbara Anne Whitney, Kevin R. Covey, Catarina Alves de Oliveira, Elaine Winston, Mark John McCaughrean, Jerome Bouvier, Sylvain Guieu, Frederick John Vrba, Jon Andrew Holtzman, Franck Marchis, Joseph Lee Hora, Lawrence Harvey Wasserman, Susan Terebey, Thomas S. Megeath, Edward Francis Guinan, Jan Forbrich, Nuria Huélamo, Pablo Riviere-Marichalar, David Barrado, Karl Roald Stapelfeldt, Jesús O Hernández, Lori E. Allen, David R. Ardila, Amelia Bayo, Fabio Favata, David James, Michael W. Werner, Kenneth Wood, American Astronomical Society

We present initial results from time-series imaging at infrared wavelengths of 0.9 deg2 in the Orion Nebula Cluster (ONC). During Fall 2009 we obtained 81 epochs of Spitzer 3.6 and 4.5 um data over 40 consecutive days. We extracted light curves with ~3% photometric accuracy for ~2000 ONC members ranging from several solar masses down to well below the hydrogen-burning mass limit. For many of the stars, we also have time-series photometry obtained at optical (Ic ) and/or near-infrared (JKs) wavelengths. Our data set can be mined to determine stellar rotation periods, identify new pre-main-sequence eclipsing binaries, search for new substellar Orion members, and help better determine the frequency of circumstellar disks as a function of stellar mass in the ONC. Our primary focus is the unique ability of 3.6 and 4.5 um variability information to improve our understanding of inner disk processes and structure in the Class I and II young stellar objects (YSOs). In this paper, we provide a brief overview of the YSOVAR Orion data obtained in Fall 2009 and highlight our light curves for AA-Tau analogs-YSOs with narrow dips in flux, most probably due to disk density structures passing through our line of sight. Detailed follow-up observations are needed in order to better quantify the nature of the obscuring bodies and what this implies for the structure of the inner disks of YSOs.