학술논문
The Astrometric Animation of Water Masers towards the Mira Variable BX Cam
Document Type
Working Paper
Author
Xu, Shuangjing; Imai, Hiroshi; Yun, Youngjoo; Zhang, Bo; Rioja, Maria J.; Dodson, Richard; Cho, Se-Hyung; Kim, Jaeheon; Cui, Lang; Sobolev, Andrey M.; Chibueze, James O.; Kim, Dong-Jin; Amada, Kei; Nakashima, Jun-ichi; Orosz, Gabor; Oyadomari, Miyako; Oh, Sejin; Yonekura, Yoshinori; Sun, Yan; Mai, Xiaofeng; Zhang, Jingdong; Wen, Shiming; Jung, Taehyun
Source
Subject
Language
Abstract
We report VLBI monitoring observations of the 22 GHz water (H$_{2}$O) masers around the Mira variable BX Cam, which were carried out as a part of the EAVN Synthesis of Stellar Maser Animations (ESTEMA) project. Data of 37 epochs in total were obtained from 2018 May to 2021 June with a time interval of 3-4 weeks, spanning approximately three stellar pulsation periods ($P= \sim$440 d). In particular, the dual-beam system equipped on the VERA stations was used to measure the kinematics and parallaxes of the H$_{2}$O maser features. The measured parallax, $\pi=1.79\pm 0.08$ mas, is consistent with $Gaia$ EDR3 and previously measured VLBI parallaxes within a 1-$\sigma$ error level. The position of the central star was estimated, based on both the $Gaia$ EDR3 data and the center position of the ring-like 43 GHz silicon-monoxide (SiO) maser distribution imaged with the KVN. The three-dimensional H$_{2}$O maser kinematics indicates that the circumstellar envelope is expanding at a velocity of $13\pm4$ km s$^{-1}$, while there are asymmetries in both the spatial and velocity distributions of the maser features. Furthermore, the H$_{2}$O maser animation achieved by our dense monitoring program manifests the propagation of shock waves in the circumstellar envelope of BX Cam.
Comment: 31 pages, 16 figures, accepted by ApJ
Comment: 31 pages, 16 figures, accepted by ApJ