Stellar Variability in a Forming Massive Star Cluster
  We present a near-infrared (NIR) variability analysis for an 6\arcmin
$\times$ 6\arcmin region, which encompasses the massive protocluster
G286.21+0.17. The total sample comprises more than 5000 objects, of which 562
show signs of a circumstellar disk based on their infrared colors. The data
includes HST observations taken in two epochs separated by 3 years in the F110W
and F160W bands. 363 objects (7% of the sample) exhibit NIR variability at a
significant level (Stetson index >1.7), and a higher variability fraction (14%)
is found for the young stellar objects (YSOs) with disk excesses. We identified
4 high amplitude (>0.6 mag) variables seen in both NIR bands. Follow up and
archival observations of the most variable object in this survey
(G286.2032+0.1740) reveal a rising light curve over 8 years from 2011 to 2019,
with a K band brightening of 3.5 mag. Overall the temporal behavior of
G286.2032+0.1740 resembles that of typical FU Ori objects, however its
pre-burst luminosity indicates it has a very low mass ($<0.12\:M_\odot$),
making it an extreme case of an outburst event that is still ongoing.
