Magnetic fields and young stellar objects in cometary cloud LDN 1616
  LDN 1615/1616 and CB 28 (hereafter, L1616) together form a cometary globule
located at an angular distance of about 8 degrees west of the Orion OB1
association, aligned roughly along the east-west direction, and showing a
distinct head-tail structure. The presence of massive stars in the Orion belt
has been considered to be responsible for the radiation driven implosion mode
of star formation in L1616. Based on the latest Gaia EDR3 measurements of the
previously known young stellar objects (YSOs) associated with L1616, we find
the distance to this cloud of 384$\pm$5 pc. We present optical polarimetry
towards L1616 that maps the plane-of-sky component of the ambient magnetic
field (B$_{POS}$) geometry. Based on the proper motion of the YSOs associated
with L1616, we investigate their plane-of-sky motion relative to the exciting
star $\epsilon$ Ori. Using the Gaia EDR3 measurements of the distances and
proper motions of the YSOs, we find two additional sources comoving with the
known YSOs. One comoving source is HD33056, a B9 star and the other might be a
young pre-main sequence star not reported in previous studies. The mean
direction of B$_{POS}$ is found to follow the cloud structure. This could be
the effect of dragging of the magnetic field lines by the impact of the
ionizing radiation from $\epsilon$ Ori. Based on the pressure exerted on L1616,
and the ages of the associated YSOs, we show that it could possibly be the main
source of ionization in L1616, and thus the star formation in it.
