Nature of continuum emission in the source of the water maser super-flare G25.65+1.04

Context. The G25.65+1.04 source is one of the few known `super-flare' water masers in the Milky Way, but in contrast to other super-flare sources, it remains the least studied. In fact, even the nature of the source driving the water maser is still unclear.
Aims: With this project, we aim to clarify the composition and properties of the G25.65+1.04 region by means of examining the parameters of the continuum sources and establishing their association with masers of different types.
Methods: Our previous VLA (Karl G. Jansky Very Large Array) observation detected four continuum peaks (VLA 1-4), three of which (VLA 1-3) were closely spaced and presented a linear orientation. However, the observation, which used the VLA B configuration, lacked the spatial resolution to resolve individual sources. A higher-resolution (A configuration) VLA observation of the continuum and spectral lines was conducted in 2019 using the L, S, C, and Ku bands.
Results: For the first time, the continuum source VLA 1 - associated with the flaring water maser - is resolved into two components: VLA 1A and 1B. The component VLA 1A and the water maser are found to spatially coincide and are thought to be powered by the same source, a protostar at an early stage of evolution showing active ejection. We argue that VLA 2 pinpoints an actively ejecting high-mass protostar, as it is associated with a 6.7 GHz methanol maser and a magnetised jet traced by a 22 GHz H₂O maser. Highly polarised OH maser emission is detected in the vicinity of VLA 1-2, with the brightest OH maser found in VLA 2. The magnetic field, identified from the OH maser emission, ranges from ∼ + 0.4 mG in VLA 1A to ∼ − 8 mG in VLA 2.
Conclusions: The G25.65+1.04 region is found to consist of at least two young stellar objects: VLA 1A and VLA 2. Both sources are found to be at an active accretion and ejection stage of evolution.

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