FLASHING: New high-velocity H2O masers in IRAS 18286−0959
Artikel i vetenskaplig tidskrift, 2020

We discovered new high-velocity components of H2O maser emission in one of the “water fountain” sources, IRAS 18286−0959, which has been monitored using the Nobeyama 45 m telescope in the FLASHING (Finest Legacy Acquisitions of SiO- and H2O-maser Ignitions by Nobeyama Generation) project since 2018 December. The maser spectra show new components with extremely high expansion velocities (>200 km s−1 projected in the line of sight), some of which are located symmetrically in the spectrum with respect to the systemic velocity. They were also mapped with KaVA (KVN and VERA Combined Array) in 2019 March. We located some of these maser components closer to the central stellar system than other high-velocity components (50-200 km s−1) that have been confirmed to be associated with the known bipolar outflow. The new components would have flashed in the fast collimated jet at a speed of over 300 km s−1 (soon) after 2011 when they had not been detected. The fastest of the new components seem to indicate rapid deceleration in these spectra; however, our present monitoring is still too sparse to unambiguously confirm it (up to 50 km s−1 yr−1) and too short to reveal their terminal expansion velocity, which will be equal to the expansion velocity that has been observed (vexp ∼ 120 km s−1). Future occurrences of such extreme-velocity components may provide a good opportunity to investigate possible recurrent outflow ignitions. Thus, the sculpture of the parental envelope will be traced by the dense gas that is entrained by the fast jet and exhibits spectacular distributions of the relatively stable maser features.

Stars: AGB and post-AGB

Stars: individuals (IRAS 18286−0959)



H. Imai

Kagoshima University

Yuri Uno

Kagoshima University

Daichi Maeyama

Kagoshima University

Ryosuke Yamaguchi

Kagoshima University

Kei Amada

Kagoshima University

Yuhki Hamae

Kagoshima University

G. Orosz

University of Tasmania

Chinese Academy of Sciences

J. F. Gomez

Instituto de Astrofisica de Andalucía (IAA)

Daniel Tafoya

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium, Observationssupport

National Astronomical Observatory of Japan

L. Uscanga

Universidad de Guanajuato

R. A. Burns

National Astronomical Observatory of Japan

Korea Astronomy and Space Science Institute

Publication of the Astronomical Society of Japan

0004-6264 (ISSN)

Vol. 72 4 psaa047


Astronomi, astrofysik och kosmologi


Fusion, plasma och rymdfysik



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