Structure of the Galactic Bulge

银河核球的结构

• 批准号: 03640244
• 负责人: NAKADA Yoshikazu
• 金额: $ 1.15万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03640244/
• 关键词: bulge; maser; rotation

The Galactic bulge has been the focus of many researches in the past decade. In 1991 we proposed the non-axisymmetric model of the bulge on the basis of the distribution of IRAS sources around the Galactic center. Subsequently, the global rotation of the bulge was detected by our SiO observation of the bulge IRAS sources.Since the total number of the maser sources in the previous study was only sixteen, systematic survey of the bulge maser source was planned at the Nobeyama Radio Observatory. It took three years to obtain the radial velocities of 124 sources in the bulge area. We determined the bulge rotation rate as 9.3km/sec/deg. which was consistent with those obtained by other methods.Although the number of sources was far from completeness, we still notice some interesting features in the velocity structure of the bulge. First, the mean rotation rate decreses with the distance from the Galactic plane. The only plausible way to compromize the differential rotation with the non-axisymmetric shape of the bulge seems to allow the existence of the internal velocity field inside the bulge. Second, there are areas where few sources were detected on the velocity-longitude diagram. Those 'holes' could be the clues to the full understanding of the velocity structure.Near infrared observation of those bulge sources were repeatedly performed at the Sutherland Observatory in South Africa. More data is needed to determine the precise periods of their light variation.

在过去的十年里，银河系的核球一直是许多研究的焦点。1991年，我们根据银河系中心附近红外天文卫星源的分布，提出了银河系核球的非轴对称模型。随后，我们对球核IRAS源的SiO观测发现了球核的全球旋转。由于以前研究中的脉泽源总数只有16个，因此计划在野边山射电天文台对球核脉泽源进行系统的观测。用了三年时间获得了隆凸区124个源的径向速度。我们确定了隆起的旋转速率为9.3公里/秒/度。虽然源的数目远未完全，但我们仍然注意到球核速度结构中一些有趣的特征。第一，平均自转速率随着离银道面的距离而减小。唯一合理的方法来折衷的微分旋转与非轴对称形状的隆起，似乎允许的内部速度场的存在的隆起。第二，有些地区在速度-经度图上几乎没有检测到源。这些“洞”可能是全面了解速度结构的线索。南非萨瑟兰天文台对这些凸起源进行了反复的近红外观测。需要更多的数据来确定它们光变化的精确周期。

项目成果

Y.Nakada et al.: "Detection of SiO and H_2O Ma_<SERS> in the Galactic Bulge SOURCES" Publ.Astron.Soc.Japan. 45. (1993)

Y.Nakada 等人：“银河系核球源中 SiO 和 H_2O Ma_<SERS> 的检测”Publ.Astron.Soc.Japan。

Izumiura,H.: "SiO Maser Survey of the Bulge IRAS Sources" IAU Symposium. 145. 303-308 (1993)

Izumiura,H.：“SiO 脉泽对核球 IRAS 源的调查”IAU 研讨会。

Y.NAKADA et al.: "Is THE BULGE OF OVR GALAXY TRIAXIAL?" NATURE. 353. 140-141 (1991)

Y.NAKADA 等人：“OVR 星系的核球是三​​轴的吗？”

Nakada,Y.: "Detection of SiO and H_2O Masers in the Galactic Bulge Sources" Publ.Astron.Soc.Japan. 45. 179-189 (1993)

Nakada,Y.：“银河核球源中 SiO 和 H_2O 脉泽的检测”Publ.Astron.Soc.Japan。