Chemical compositions in the vicinity of protostars in Ophiuchus
  We have analyzed Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 4
Band 6 data toward two young stellar objects (YSOs), Oph-emb5 and Oph-emb9, in
the Ophiuchus star-forming region. The YSO Oph-emb5 is located in a relatively
quiescent region, whereas Oph-emb9 is irradiated by a nearby bright Herbig Be
star. Molecular lines from $cyclic$-C$_{3}$H$_{2}$ ($c$-C$_{3}$H$_{2}$),
H$_{2}$CO, CH$_{3}$OH, $^{13}$CO, C$^{18}$O, and DCO$^{+}$ have been detected
from both sources, while DCN is detected only in Oph-emb9. Around Oph-emb5,
$c$-C$_{3}$H$_{2}$ is enhanced at the west side, relative to the IR source,
whereas H$_{2}$CO and CH$_{3}$OH are abundant at the east side. In the field of
Oph-emb9, moment 0 maps of the $c$-C$_{3}$H$_{2}$ lines show a peak at the
eastern edge of the field of view, which is irradiated by the Herbig Be star.
Moment 0 maps of CH$_{3}$OH and H$_{2}$CO show peaks farther from the bright
star. We derive the $N$($c$-C$_{3}$H$_{2}$)/$N$(CH$_{3}$OH) column density
ratios at the peak positions of $c$-C$_{3}$H$_{2}$ and CH$_{3}$OH near each
YSO, which are identified based on their moment 0 maps. The
$N$($c$-C$_{3}$H$_{2}$)/$N$(CH$_{3}$OH) ratio at the $c$-C$_{3}$H$_{2}$ peak is
significantly higher than at the CH$_{3}$OH peak by a factor of $\sim 19$ in
Oph-emb9, while the difference in this column density ratio between these two
positions is a factor of $\sim2.6 $ in Oph-emb5. These differences are
attributed to the efficiency of the photon-dominated region (PDR) chemistry in
Oph-emb9. The higher DCO$^{+}$ column density and the detection of DCN in
Oph-emb9 are also discussed in the context of UV irradiation flux.
