Flaring water masers associated with W49N

¹ Radio Astronomy Laboratory of Crimean Astrophysical Observatory, Katsively RT-22, Crimea
e-mail: volvach@meta.ua
² Institute of Applied Astronomy, Russian Academy of Sciences, St. Petersburg, Russia
³ Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences, Profsoyuznaya ul. 84/32, Moscow 117997, Russia
⁴ Hartebeesthoek Radio Astronomy Observatory, PO Box 443, Krugersdorp 1740, South Africa
⁵ The University of Western Ontario, 1151 Richmond Street, London, ON N6A 3K7, Canada
⁶ Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun, Poland
⁷ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁸ National Astronomical Research Institute of Thailand, 260 Moo 4, T. Donkaew, A. Maerim, Chiangmai 50180, Thailand
⁹ INAF, Istituto di Radioastronomia, Via Gobetti 101, 40129 Bologna, Italy
¹⁰ Italian Alma Regional Centre, Istituto di Radioastronomia, Via Gobetti 101, 40129 Bologna, Italy
¹¹ INAF, Observatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius (CA), Italy

Received: 22 March 2019
Accepted: 11 July 2019

Abstract

Aims. We present our monitoring observations and analysis of water masers associated with W49N taken in 2017 and 2018. A significant flare occurred during these observations.

Methods. We used ground-based radio telescopes in Simeiz (RT-22), Torun (RT-32), Medicina (RT-32), Effelsberg (RT-100) with broadband spectrometers. Observational data were collected and processed automatically.

Results. We report a powerful flare of the v = +6 km s⁻¹ water maser feature; it increased in over ten months to S_{1.3 cm} = 84 kJy in 2017 December, then decayed to the pre-flare quiescent value of S_{1.3 cm} = 8.7 kJy in 2018 August. We infer that this flaring feature is unsaturated based on the relationship between line width and flux density.