Wide Field CO Mapping in the Region of IRAS 19312+1950
  We report the results of a wide field CO mapping in the region of IRAS
19312+1950. This IRAS object exhibits SiO/H$_2$O/OH maser emission, and is
embedded in a chemically-rich molecular component, of which the origin is still
unknown. In order to reveal the entire structure and gas mass of the
surrounding molecular component for the first time, we have mapped a wide
region around IRAS 19312+1950 in the $^{12}$CO $J=1-0$, $^{13}$CO $J=1-0$ and
C$^{18}$O $J=1-0$ lines using the Nobeyama 45m telescope. In conjunction with
the archival CO maps, we investigated a region with a size up to $20' \times
20'$ around this IRAS object. We calculated CO gas mass assuming the LTE
condition, a stellar velocity against to the interstellar medium assuming an
analytic model of a bow shock, and absolute luminosity using the latest
archival data and trigonometric parallax distance. The derived gas-mass (225
M$_{\odot}$ $-$ 478 M$_{\odot}$) of the molecular component and the relatively
large luminosity ($2.63\times10^{4}$ L$_{\odot}$) suggest that the central
SiO/H$_2$O/OH maser source seems to be a red supergiant (RSG) rather than an
asymptotic giant branch (AGB) star or post-AGB star.
