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Water Fountain Sources Monitored in FLASHING

Published online by Cambridge University Press:  07 February 2024

Hiroshi Imai*
Affiliation:
Amanogawa Galaxy Astronomy Research Center, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan. Center for General Education, Institute for Comprehensive Education, Kagoshima University, 1-21-30 Korimoto, Kagoshima 890-0065, Japan; e-mail: hiroimai@km.kagoshima-u.ac.jp
Kei Amada
Affiliation:
Graduate School of Science and Engineering, Kagoshima University, Kagoshima 890-0065, Japan
José F. Gómez
Affiliation:
Instituto de Astrofísica de Andalucía, CSIC, Granada E-18008, Spain
Lucero Uscanga
Affiliation:
Departamento de Astronomía, Universidad de Guanajuato, Guanajuato 36000, Mexico
Daniel Tafoya
Affiliation:
Department of Space, Earth and Environment, Chalmers University of Technology, Onsala 439 92, Sweden
Keisuke Nakashima
Affiliation:
Faculty of Science, Kagoshima University, Kagoshima 890-0065, Japan
Ka-Yiu Shum
Affiliation:
Faculty of Science, Kagoshima University, Kagoshima 890-0065, Japan
Yuhki Hamae
Affiliation:
Faculty of Science, Kagoshima University, Kagoshima 890-0065, Japan
Ross A. Burns
Affiliation:
National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan RIKEN, Wako, Saitama 351-0198, Japan
Yosuke Shibata
Affiliation:
Faculty of Science, Kagoshima University, Kagoshima 890-0065, Japan
Rina Kasai
Affiliation:
Faculty of Science, Kagoshima University, Kagoshima 890-0065, Japan
Miki Takashima
Affiliation:
Faculty of Science, Kagoshima University, Kagoshima 890-0065, Japan
Gabor Orosz
Affiliation:
Joint Institute for VLBI ERIC, Dwingeloo 7900, Netherlands

Abstract

We have investigated the spectral evolutions of H2O and SiO masers associated with 12 “water fountain” sources in our FLASHING (Finest Legacy Acquisitions of SiO-/H2O-maser Ignitions by Nobeyama Generation) project. Our monitoring observations have been conducted using the Nobeyama 45 m telescope every 2 weeks–2 months since 2018 December except during summer seasons. We have found new extremely high velocity H2O maser components, breaking the records of jet speeds in this type of sources. Systematic line-of-sight velocity drifts of the H2O maser spectral peaks have also been found, indicating acceleration of the entrained material hosting the masers around the jet. Moreover, by comparing with previous spectral data, we can find decadal growths/decays of H2O maser emission. Possible periodic variations of the maser spectra are further being inspected in order to explore the periodicity of the central stellar system (a pulsating star or a binary). Thus we expect to see the real-time evolution/devolutions of the water fountains over decades.

Type
Contributed Paper
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of International Astronomical Union

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