Bowshocks in a newly discovered maser source in IRAS 20231+3440
  From measuring the annual parallax of water masers over one and a half years
with VERA, we present the trigonometric parallax and corresponding distance of
another newly identified water maser source in the region of IRAS 20231+3440 as
$\pi=0.611\pm0.022$ mas and $D=1.64\pm0.06$ kpc respectively. We measured the
absolute proper motions of all the newly detected maser spots (30 spots) and
presented two pictures describing the possible spatial distribution of the
water maser as the morphology marks out an arc of masers whose average proper
motion velocity in the jet direction was 14.26 km s$^{-1}$. As revealed by the
ALLWISE composite image, and by applying the colour-colour method of YSO
identification and classification on photometric archived data, we identified
the driving source of the north maser group to be a class I, young stellar
object. To further probe the nature of the progenitor, we used the momentum
rate maximum value (1.2$\times$10$^{-4}$ M$_{\odot}$ yr$^{-1}$ km s$^{-1}$) of
the outflow to satisfy that the progenitor under investigation is a low mass
young stellar object concurrently forming alongside an intermediate-mass YSO
$\sim 60,000$ au ($\sim 37$ arcsecs) away from it.
