Thomas S. Megeath

YSOVAR: THE FIRST SENSITIVE, WIDE-AREA, MID-INFRARED PHOTOMETRIC MONITORING OF THE ORION NEBULA CLUSTER

We present initial results from time-series imaging at infrared wavelengths of 0.9 deg^2 in the Orion Nebula Cluster (ONC). During Fall 2009 we obtained 81 epochs of Spitzer 3.6 and 4.5 μm 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 (I_c) and/or near-infrared (JK_s ) 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 μm 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.

A Herschel-SPIRE survey of the Mon R2 giant molecular cloud: analysis of the gas column density probability density function

We present a far-IR survey of the entire Mon R2 GMC with

A Spitzer Space Telescope Study of Disks in the Young σ Orionis Cluster

Herschel-SPIRE

Deep GLIMPSE: Exploring the Far Side of the Galaxy

cross-calibrated with

An IRAC Survey of the L1630 and L1641 (Orion) Molecular Clouds

Planck-HFI

Protostars in Orion: New results from the Herschel Orion Protostar Survey Key Program

data. We fit the SEDs of each pixel with a greybody function and an optimal beta value of 1.8. We find that mid-range column densities obtained from far-IR dust emission and near-IR extinction are consistent. For the entire GMC, we find that the column density histogram, or N-PDF, is lognormal below

Recent Results from the Herschel Orion Protostar Survey

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YSO variability in Massive Star-forming Regions

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Herschel PACS Spectroscopy of Spitzer identified Protostars in the Orion Molecular Clouds

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Mid-IR Variability of YSOs in the Large, Evolved, Young Cluster, Cep OB3b

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