Astrophys. J., 733, 113 (2011/June-1)
Disk evolution in OB associations: deep Spitzer/IRAC observations of IC 1795.
ROCCATAGLIATA V., BOUWMAN J., HENNING T., GENNARO M., FEIGELSON E., KIM J.S., SICILIA-AGUILAR A. and LAWSON W.A.
Abstract (from CDS):
We present a deep Spitzer/Infrared Array Camera (IRAC) survey of the OB association IC 1795 carried out to investigate the evolution of protoplanetary disks in regions of massive star formation. Combining Spitzer/IRAC data with Chandra/Advanced CCD Imaging Spectrometer observations, we find 289 cluster members. An additional 340 sources with an infrared excess, but without X-ray counterpart, are classified as cluster member candidates. Both surveys are complete down to stellar masses of about 1 M☉. We present pre-main-sequence isochrones computed for the first time in the Spitzer/IRAC colors. The age of the cluster, determined via the location of the Class III sources in the [3.6]-[4.5]/[3.6] color-magnitude diagram, is in the range of 3-5 Myr. As theoretically expected, we do not find any systematic variation in the spatial distribution of disks within 0.6 pc of either O-type star in the association. However, the disk fraction in IC 1795 does depend on the stellar mass: sources with masses >2 M☉ have a disk fraction of ∼20%, while lower mass objects (2-0.8 M☉) have a disk fraction of ∼50%. This implies that disks around massive stars have a shorter dissipation timescale.
ISM: individual: W3 - open clusters and associations: individual: IC1795 - protoplanetary disks - stars: formation - stars: pre-main sequence - X-rays: stars
VizieR on-line data:
<Available at CDS (J/ApJ/733/113): table2.dat table3.dat table4.dat table5.dat>
Tables 2-5: [RBH2011] IRAC JHHMMSSss+DDMMSSs N=271+247.
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