Limits of water maser kinematics: insights from the high-mass protostar AFGL 5142-MM1
Document Type
Article
Publication Date
2-1-2024
Abstract
Multi-epoch very long baseline interferometry (VLBI) observations measure three-dimensional water maser motions in protostellar outflows, enabling analysis of inclination and velocity. However, these analyses assume that water masers and shock surfaces within outflows are co-propagating. We compare VLBI data on maser-traced bow shocks in the high-mass protostar AFGL 5142-MM1, from seven epochs of archival data from the VLBI Exploration of Radio Astrometry (VERA), obtained from 2014 April to 2015 May, and our newly conducted data from the KVN and VERA Array (KaVA), obtained in 2016 March. We find an inconsistency between the expected displacement of the bow shocks and the motions of individual masers. The separation between two opposing bow shocks in AFGL 5142-MM1 was determined to be 337.17 +/- 0.07 mas in the KaVA data, which is less than an expected value of 342.1 +/- 0.7 mas based on extrapolation of the proper motions of individual maser features measured by VERA. Our measurements imply that the bow shock propagates at a velocity of 24 +/- 3 km s(-1), while the individual masing gas clumps move at an average velocity of 55 +/- 5 km s(-1); that is ,the water masers are moving in the outflow direction at double the speed at which the bow shocks are propagating. Our results emphasize that investigations of individual maser features are best approached using short-term high-cadence VLBI monitoring, while long-term monitoring on timescales comparable to the lifetimes of maser features is better suited to tracing the overall evolution of shock surfaces. Observers should be aware that masers and shock surfaces can move relative to each other, and that this can affect the interpretation of protostellar outflows.
Keywords
masers, stars: individual: AFGL 5142-MM1, stars: massive, ISM: jets and outflows
Divisions
mathematics,PHYSICS
Funders
Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) (GPF081A-2020),UM's Faculty of Science grant (17K05398); (20H05845),Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (KAKENHI) (2022YFA1603101),National Key Research & Development Program of China (12073061); (12122307),National Natural Science Foundation of China (NSFC) (114231KYSB20200009),Chinese Academy of Sciences (20PJ1415500),Shanghai Pujiang Program (NRF-2019R1A2C1010851),National Research Foundation of Korea (2023-1-84000),Korea Astronomy and Space Science Institute - Korea government (MSIT) (FEUZ-2023-0019),Ministry of Science and Higher Education of the Russian Federation
Publication Title
Monthly Notices of the Royal Astronomical Society
Volume
527
Issue
4
Publisher
Oxford University Press
Publisher Location
GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND