SiO Maser Survey off the Galactic Plane: A Signature of Streaming Motion

A group of Mira variables in the solar neighborhood show unusual spatial motion in the Galaxy. To study this motion in a much larger scale in the Galaxy, we newly surveyed 134 evolved stars off the Galactic plane by SiO maser lines, obtaining accurate radial velocities of 84 detected stars. Together with the past data of SiO maser sources, we analyzed the radial velocity data of a large sample of sources distributing in a distance range of about 0.3 -- 6 kpc in the first Galactic quadrant. At the Galactic longitudes between 20 and 40 deg, we found a group of stars with large negative radial velocities, which deviate by more than 100 km s^{-1} from the Galactic rotation. We show that these deviant motions of maser stars are created by periodic gravitational perturbation of the Bulge bar, and that the effect appears most strongly at radii between corotation and outer Lindblad resonances. The resonance effect can explain the displacement of positions from the Galactic plane as well.Comment: 14 pages, 11 figures, PASJ, 62. No. 3 in press high resolution figures available from http://www.nro.nao.ac.jp/~lib_pub/report/data/no675.pd

A Search for Water Masers in the Saturnian System

We searched for H2O 6(1,6)-5(2,3) maser emission at 22.235 GHz from several Saturnian satellites with the Nobeyama 45m radio telescope in May 2009. Observations were made for Titan, Hyperion, Enceladus and Atlas, for which Pogrebenko et al. (2009) had reported detections of water masers at 22.235 GHz, and in addition for Iapetus and other inner satellites. We detected no emission of the water maser line for all the satellites observed, although sensitivities of our observations were comparable or even better than those of Pogrebenko et al.. We infer that the water maser emission from the Saturnian system is extremely weak, or sporadic in nature. Monitoring over a long period and obtaining statistical results must be made for the further understanding of the water maser emission in the Saturnian system.Comment: 8 pages, 2 figures, accepted for publication in PASJ (Letter

Interaction between Northern Coal Sack in the Cyg OB 7 cloud complex and the multiple super nova remnants including HB 21

We report possible interaction between multiple super nova remnants (SNRs) and Northern Coal Sack (NCS) which is a massive clump (~1000 Mo) in the Cyg OB 7 cloud complex and is forming a massive Class 0 object. We performed molecular observations of the 12CO(J=1-0), 13CO(J=1-0), and C18O(J=1-0) emission lines using the 45m telescope at the Nobeyama Radio Observatory, and we found that there are mainly four velocity components at Vlsr=-20, -6, -4, and 10 km/s. The -6 and -4 km/s components correspond to the systemic velocities of NCS and the Cygnus OB 7 complex, respectively, and the other velocity components originate from distinct smaller clouds. Interestingly, there are apparent correlations and anti-correlations among the spatial distributions of the four components, suggesting that they are physically interacting with one another. On a larger scale, we find that a group of small clouds belonging to the -20 and 10 km/s components are located along two different arcs around some SNRs including HB 21 which has been suggested to be interacting with the Cyg OB 7 cloud complex, and we also find that NCS is located right at the interface of the arcs. The small clouds are likely to be the gas swept up by the stellar wind of the massive stars which created the SNRs. We suggest that the small clouds alined along the two arcs recently encountered NCS and the massive star formation in NCS was triggered by the strong interaction with the small clouds.Comment: To appear in the Publications of the Astronomical Society of Japan (PASJ