Protostars and Planets VI, Heidelberg, July 15-20, 2013
EXTERNALLY INDUCED DISKS PHOTOEVAPORATION IN THE MASSIVE CLUSTER CYGNUS OB2
Guarcello, Mario (Harvard-Smithsonian Center for Astrophysics)
CygnusOB2, the most massive OB association of the Cygnus-X region, hosts more than 2000 OB stars and a population of young pre-Main Sequence stars. It is 1.4kpc distant from the Sun and the best target to study star formation and disk evolution in the presence of a large number of massive stars. We present a multiwavelength study of protoplanetary disks in Cyg OB2, based on new deep optical and X-ray data obtained with OSIRIS@GTC and Chandra/ACIS-I (the Cygnus OB2 Chandra Legacy Survey), and on archival data from 2MASS, UKIDSS, IPHAS and the Spitzer Legacy Survey of the Cygnus-X Region. We compare the spatial variation of disk fraction with the intensity of the ionized flux emitted by the OB members of CygOB2. We show that the disk fraction decreases gradually with increasing the intensity of the ionizing flux. The results suggests protoplanetary disks in Cyg OB2 suffer long-range photoevaporation induced by the OB star population. This is different than the results obtained in the study of NGC6611 (i.e. Guarcello et al 2007), NGC2264 (i.e. Balog et al. 2007), and the Trapezium in Orion (i.e. Storzer & Hollenbach 1999), where disk fraction drops only in the proximity of the OB stars. We discuss this difference in terms of the larger ionizing flux and older age in Cyg OB2 with respect to these other clusters and touch upon the relevance of this work for planet formation in the universe.
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