TY - JOUR

T1 - Limits of water maser kinematics: insights from the high-mass protostar AFGL 5142-MM1

AU - Rosli, Zulfazli

AU - Burns, Ross

AU - Nazri, Affan Adly

AU - Sugiyama, Koichiro

AU - Hirota, Tomoya

AU - Kim, Kee-Tae

AU - Yonekura, Yoshinori

AU - Tie, Liu

AU - Orosz, Gabor

AU - Chibueze, James

AU - Sobolev, Andrey

AU - Kang, Ji Hyun

AU - Lee, Chang Won

AU - Hwang, Jihye

AU - Mohammad, Hafieduddin

AU - Hashim, Norsiah

AU - Abidin, Zamri Zainal

N1 - ZR acknowledges the support provided by UM’s Faculty of Science grant (GPF081A-2020), which has enabled the completion of this research and the publication of its findings. TH is supported by the MEXT/JSPS KAKENHI Grant Numbers 17K05398 and 20H05845. TL acknowledges supports from the National Key Research and Development Programme of China (No. 2022YFA1603101); the National Natural Science Foundation of China (NSFC), through grants No. 12073061 and No. 12122307; the international partnership programme of the Chinese Academy of Sciences, through grant No. 114231KYSB20200009; and the Shanghai Pujiang Programme 20PJ1415500. CWL is supported by the Basic Science Research Programme through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2019R1A2C1010851), and by the Korea Astronomy and Space Science Institute grant funded by the Korea government (MSIT) (Project No. 2023-1-84000). AMS was supported by Ministry of Science and Higher Education of the Russian Federation (state contract FEUZ-2023-0019).

PY - 2024/2

Y1 - 2024/2

N2 - 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.

AB - 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.

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U2 - 10.1093/mnras/stad3767

DO - 10.1093/mnras/stad3767

M3 - Article

VL - 527

SP - 10031

EP - 10037

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 4

ER -