What's Behind the Elephant's Trunk? Identifying Young Stellar Objects on
  the Outskirts of IC1396
  Empirically, the estimated lifetime of a typical protoplanetary disk is
$<5-10$ Myr. However, the disk lifetimes required to produce a variety of
observed exoplanetary systems may exceed this timescale. Some hypothesize that
this inconsistency is due to estimating disk fractions at the cores of
clusters, where radiation fields external to a star-disk system can
photoevaporate the disk. To test this, we have observed a field on the western
outskirts of the IC 1396 star-forming region with \textit{XMM-Newton} to
identify new Class III YSO cluster members. Our X-ray sample is complete for
YSOs down to $1.8\,M_{\odot}$. We use a subset of these X-ray sources that have
near- and mid-infrared counterparts to determine the disk fraction for this
field. We find that the fraction of X-ray-detected cluster members that host
disks in the field we observe is $17_{-7}^{+10}\%$ (1$\sigma$), comparable with
the $29_{-3}^{+4}\%$ found in an adjacent field centered on the cometary
globule IC 1396A. We re-evaluate YSO identifications in the IC 1396A field
using \textit{Gaia} parallaxes compared to previous color-cut-only
identifications, finding that incorporating independent distance measurements
provides key additional constraints. Given the existence of at least one
massive star producing an external radiation field in the cluster core, the
lack of statistically significant difference in disk fraction in each observed
field suggests that disk lifetimes remain consistent as a function of distance
from the cluster core.
