Search for Astronomical Maser Sources and Reference Radio Sources for VLBI Astrometry

寻找 VLBI 天体测量的天文脉泽源和参考射电源

• 批准号: 07404009
• 负责人: SASAO Tetsuo
• 金额: $ 23.42万
• 依托单位: National Astronomical Observatory
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07404009/
• 关键词: maser source; differential VLBI; fast switching; annual parallax; Project VERA; star formation; phase compensation; J-net; メーザー源; VLBI; 基準電波源; 視線速度変化; クエ-サ; 相対VLBI; 位置天文; メ-ザ源

Results of present research as summarized below clearly confirmed feasibility of the the high-precision Galactic astorometry aimed at in VERA (VLBI Exploration of Radio Astrometry) Project.(1) Search for Reference Radio SourcesStatistical survey using radio-source catalogs and VLBI observations showed that at least one compact and bright enough reference-source candidate is normally found within 2 degrees from any target source.(2) Physical Properties of Maser SourcesDomestic VLBI observations revealed existence of water maser spots around late-type stars which are not resolved with 1000km baseline, surviving longer than a half year and, therefore, suited to VLBI astrometry. Systematic shift (acceleration) in line-of-sight velocity of the stellar maser spots was detected for the first time. New maser spots were discovered in Ori-KL sar-forming region which are almost aligned along the symmetry axis of the bipolar outflow and possibly associated with the jet-activity of the central youn … More g stellar object.(3) Test Observation for Maser AstrometryFringe-phase-difference observable was successfully detected between two adjacent quasars at 22 GHz in a switching differential VLBI experiment carried out with Japanese domestic VLBI Network (J-net).(4) Compensation of Atmospheric Phase FluctuationsExperiments using Nobeyama Millimeter Array and numerical simulations based on a statistical model of the turbulent troposphere demonstrated high performance expected in the phase compensation by means of the differential VLBI provided that the target and reference sources are separated by no more than a few degrees.The simulations also revealed effectiveness of the phase compensation in terms of the fast-switching defferential VLBI with the switching cycle of 10-20 second at observing frequency up to 22-43 GHz.(5) Estimation of Astrometric AccuracyEstimated accuracy of the annual parallax determination with VERA array based on a model simulation was better than 10 microarcsecond for a pair of point-like maser and quasar sources observed in favorable atmospheric conditions. Less

目前的研究结果总结如下，清楚地证实了VERA（VLBI射电天体测量）项目所针对的高精度银河天体测量的可行性。（1）参考射电源的搜索利用射电源目录和VLBI观测进行的统计调查表明，通常在距任何目标源2度以内都可以找到至少一个紧凑且足够明亮的参考源候选者。（2）物理特性 国内VLBI观测揭示了晚型恒星周围存在水脉泽斑，这些水脉泽斑无法用1000公里基线分辨出来，存活时间超过半年，因此适合VLBI天体测量。首次检测到恒星微波激射点视线速度的系统性移动（加速度）。在 Ori-KL sar 形成区发现了新的脉泽斑，这些斑几乎沿着双极流出的对称轴排列，可能与中央年轻 g 星体的喷流活动有关。(3) 脉泽天体测量测试观测在与日本国内进行的切换差分 VLBI 实验中，在 22 GHz 下成功检测到两个相邻类星体之间的条纹相位差观测 VLBI 网络 (J-net)。(4) 大气相位涨落补偿使用野边毫米波阵进行的实验和基于湍流对流层统计模型的数值模拟证明，只要目标源和参考源相距不超过几度，通过差分 VLBI 进行相位补偿即可实现预期的高性能。模拟还揭示了相位补偿在以下方面的有效性： 快速切换的差分VLBI，观测频率高达22-43 GHz，切换周期为10-20秒。(5)天体测量精度估计基于模型模拟，对于在有利的大气条件下观测的一对点状脉泽和类星体源，VERA阵列年视差确定的估计精度优于10微角秒。较少的

项目成果

Sasao,T.,Asaki,Y.,Okudaira,A.and Omodaka,T.: "Reference-Radio-Source Candidates for VERA Observations" Proceedings of Technical Wordshop for APT and APSG 1996. (in press). (1997)

Sasao,T.、Asaki,Y.、Okudaira,A. 和 Omodaka,T.：“VERA 观测的参考无线电源候选”APT 和 APSG 1996 年技术 Wordshop 会议记录。（正在印刷中）。

Hanada,H.,Kawano,N.,Ooe,M.,Heki,K.,Araki,H.,et al.: "Scientific goal of VLBI observtion of radio Soures on the Moon and a Lunar orbiter" Proc.29th ISAS Lunar and Planetary Symposium. 12-15 (1996)

Hanada,H.,Kawano,N.,Ooe,M.,Heki,K.,Araki,H.,et al.：“VLBI 观测月球和月球轨道器上的射电源的科学目标”Proc.29th ISAS

原忠徳,佐藤克久 久慈清助: "VERAの信号伝送系について(Signal Transmission System of VERA)" 1995年度VLBIシンポジウム. (印刷中). (1996)

Tadanori Hara、Katsuhisa Sato、Kiyosuke Kuji：“VERA 信号传输系统”1995 VLBI 研讨会（1996 年）。

亀谷 収: "VERAでもとまる距離と固有運動の重要性" 「我が未開の大銀河」研究会集録. 124-128 (1995)

Osamu Kametani：“VERA 中停止距离和自行运动的重要性”“我的未探索的伟大星系”研究小组论文集 124-128 (1995)。

Hanada, H., Kawano, N., Ooe, M., Heki, K., Tsuruta, S., Araki, H.: "Differential VLBI Observations of satellite and Lunar-surface Radio Emitters (in Japanese)" Proceedings of 1996 VLBI Sumposium. 78-81 (1997)

Hanada, H.、Kawano, N.、Ooe, M.、Heki, K.、Tsuruta, S.、Araki, H.：“卫星和月球表面无线电发射器的差分 VLBI 观测（日语）”1996 年会议记录