  An exotic environment surrounds the young stellar groups associated with the
Canis Major (CMa) OB1/R1 region, which probably was formed under feedback from
at least three supernova events having occurred a few million years ago. We use
astrometric data from the Gaia-DR2 to confirm the membership of the stars in
CMa R1, based on proper motion and parallax, which revealed 514 new members and
candidates. The mean age of 5 Myr estimated from the color-magnitude diagram
characterizes the sources as likely pre-main sequence candidates. In total, a
sample of 694 stars detected with the T80-South telescope was analyzed
according to different color-color diagrams, which were compared with
theoretical colors from evolutionary models, aiming to reveal the objects that
exhibit color excess due to accretion processes. Accretion and magnetic
activity were also explored on the basis of empirical flux-flux relation, such
as F660 and F861 that are related to Halpha and Ca II triplet emission,
respectively. A low fraction (3 percent) of the sample have Halpha excess and
other colors expected for stars exhibiting chromospheric activity. The number
of Class I and Class II objects, identified by the infrared (WISE) colors,
indicates a disk fraction of 6 percent, which is lower than the expected for
stellar clusters with similar age. A such large sample of objects associated
with CMa R1 without evidences of circumstellar accretion can be interpreted as
a lack of disk-bearing stars, unusual for young star-forming regions. However,
this may be explained as the result of supernova events.
