Observational Study of the SiO Maser Sources at the Galactic Center Region

这项研究通过利用射电望远镜测量晚型恒星在氧化硅(SiO)脉泽线上恒星的径向速度，来探索银心附近环境中的物理问题。我们在H10和H11学年完成了以下射电和红外观测。(1)用Nobeama的45米射电望远镜在SiO脉泽线上观测到了银河盘中600个颜色选择的IRAS源，共探测到300个。通过分析得到的恒星的径向速度，我们发现一组恒星偏离了从气体运动得知的银河系自转。(2)我们与澳大利亚国立大学在同一地区对约500个震源进行了JHK的测光和成像观测。2.3米红外望远镜。根据视星等，我们估计了到物体的距离。从这项研究中，揭示了以下事实。(1)在距银心10度以内的IRAS源中，有很大一部分被认为是膨胀星。位于银心前面的恒星子集表现出较大的负(-46公里/S)平均径向速度，而位于银心后面的恒星子集呈现正径向速度。这里的距离是从12微米和25微米的红外强度推算出来的。(3)这种现象被解释为恒星在棒状凸起中的流动运动，棒状凸起的近端位于银河经度的第一象限，恒星轨道沿棒形势拉长。S.Deguchi博士策划和指导了这项研究，并分析了近红外测光数据。Miyoshi博士分析了射电频谱数据，并进行了VLBI观测。

This research explores the physics in the environment near the galactic center with measuring the radial velocities of stars in the silicon monoxide (SiO) maser lines from late type stars by a radio telescope. We have completed the following radio and infrared observations in Hl0 and H11 academic years. (1) 600 color-selected IRAS sources in the galactic disk have been observed in SiO maser lines with the 45-m radio telescope at Nobeyama., resulting 300 detection. From analyzing the obtained radial velocities of stars, we found a group of the stars being deviant from the galactic rotation which was known from the gas motion. (2) We made the JHK photometric and imaging observations for about 500 sources in the same region with the Australian National Univ. 2.3-m infrared telescope. From the apparent magnitudes, we estimated the distances to the objects.From this research, the following facts are revealed. (1) large percentages of IRAS sources which are located within 10 degree from the galactic center are considered to be the bulge stars. A subset of stars located in front of the galactic center exhibits a large negative (-46 km/s) average radial velocity, and those behind, a positive radial velocity,. Here the distance were deduced from the infrared intensities at 12 and 25 micron. (3) This phenomenon is interpreted as a streaming motion of stars in the bar-like bulge; the near end of the bar is located at the first quadrant of the galactic longitude and the stellar orbits are elongated along the bar potential. Dr. S. Deguchi planned and directed the research and analyzed the near-infrared photometric data. Dr. Miyoshi analyzed the radio spectral data and performed the VLBI observations.