Study of a compact source with an enhanced NH$_2$D/NH$_3$ abundance ratio in the S187 region

When analyzing data obtained with the Onsala 20-m radio telescope (Sweden) in 2018, a compact peak of NH$_2$D emission with an enhanced ratio of NH$_2$D/NH$_3$ column densities was discovered in the S187 region. This peak is not associated with any known astronomical object from the SIMBAD database, but previously obtained dust emission maps have a peak in this region. Additional observations of this region were carried out in 2023 with the Onsala telescope. The kinetic temperature in the center of the source was determined using the rotational diagrams of the CH$_3$CN and CH$_3$CCH molecules, and it turned out to be quite high (according to various estimates, approximately from 30 K to 50 K). Based on the spectra of the C$^{18}$O molecule and dust emission, estimates of the column density of molecular hydrogen were obtained. Deuterated NH$_2$D and DCO$^+$ molecules were detected in this region, while no noticeable emission of the DCN molecule was detected. Estimates of the column densities at the center of the source were obtained by processing the spectra of NH$_2$D, DCO$^+$, HC$^{18}$O$^+$ and HC$_3$N molecules. Maps of the integral intensities of these molecules were also constructed. The ratio of the abundances of ortho- and para-NH$_2$D, as well as the ratio of NH$_2$D and the main isotopologue of NH$_3$ were found. The possible nature of the source is discussed.