LBA observations for project V576 semester 2020OCTS

The nearest AGB star R Dor is one of the best targets of VLTI and ALMA for the study of the physical, chemical, and dynamical properties of the AGB star. There are controversies on if there is strong wind acceleration or slower wind in its circumstellar environment (CSE), and if the measured rotation is from the rotating star of a rotating disk. Therefore, we propose multi-epoch phase-referencing LBA observations of 22 GHz H2O masers toward R Dor to measure their 3D kinematics. This project can provide (1) the transverse velocity to verify the rotation, and (2) the proper motions and possible acceleration in CSE, which also will show the maser kinematics dominated by radial expansion or collimated jets.

距离地球最近的渐近巨星分支（Asymptotic Giant Branch, AGB）星R Dor，是甚大望远镜干涉仪（Very Large Telescope Interferometer, VLTI）与阿塔卡马大型毫米/亚毫米波阵列（Atacama Large Millimeter/submillimeter Array, ALMA）开展AGB星物理、化学及动力学特性研究的最优观测目标之一。目前学界关于其星周环境（CSE）中存在强风加速过程还是低速星风，以及观测到的自转信号源自恒星自身自转还是旋转盘自转，尚存争议。为此，我们提出针对R Dor开展多历元相位参考长基线阵列（Long Baseline Array, LBA）观测，以探测22 GHz水脉泽（H2O masers）的三维运动学特征。本项目将达成两大科学目标：其一，通过测量横向速度验证自转信号的来源；其二，获取星周环境中的自行运动与潜在的风加速现象，同时厘清脉泽运动学究竟由径向膨胀主导，还是受准直喷流所支配。