A study of accretion and disk diagnostics in the NGC 2264 cluster
  Understanding disk dissipation is essential for studying how planets form.
Disk gaps and holes, which almost correspond to dust-free regions, are inferred
from infrared observations of T Tauri stars (TTS), indicating the existence of
a transitional phase between thick accreting disks and debris disks. Transition
disks are usually referred to as candidates for newly formed planets. We
searched for transition disk candidates belonging to NGC 2264. We characterized
accretion, disk, and stellar properties of transition disk candidates and
compared them to systems with a full disk and diskless stars We modeled the
spectral energy distribution (SED) of a sample of 401 TTS, with Hyperion SED
fitting code using photometric data from the U band to the MIPS band. We used
the SED modeling to distinguish transition disk candidates, full disk systems,
and diskless stars. We classified $52\%$ of the sample as full disk systems,
$41\%$ as diskless stars, and $7\%$ of the systems as transition disk
candidates, among which seven systems are new transition disk candidates
belonging to the NGC 2264 cluster. The sample of transition disk candidates
present dust in the inner disk similar to anemic disks, according to the
$\alpha_{IRAC}$ classification, which shows that anemic disk systems can be
candidate transition disks. We show that the presence of a dust hole in the
inner disk does not stop the accretion process since $82\%$ of transition disk
candidates accrete and show $H\alpha$, UV excess, and mass accretion rates at
the same level as full disk systems. We estimate the inner hole sizes, ranging
from 0.1 to $78AU$, for the sample of transition disk candidates. In only
$18\%$ of the transition disk candidates, the hole size could be explained by
X-ray photoevaporation from stellar radiation.
