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28th of August 2018
ATCA observations of a water fountain nebula
by Perez-Sanchez et al.
Water Fountain nebulae are low- to intermediate-mass stars undergoing the late stages of an intense mass-loss process. The velocity and the spatial distribution of water maser spectral features can provide information about the kinematics of the molecular gas component of their circumstellar envelopes. Perez-Sanchez et al. recently presented preliminary results of observations of the Water Fountain nebula IRAS 15445-5449 using the Australia Telescope Compact Array and the Very Large Telescope (SINFONI/VLT). Assuming that the pumping of the water maser transitions is a consequence of shocks between different velocity winds, the spatial distribution of the emission shed light on the scales of the regions affected by the propagation of the shock-fronts.

The image above shows the spatial distribution of the 22 GHz H2O maser spectral features detected in 2007, which Perez-Sanchez compare to a second epoch taken in 2012. The offsets are with respect to the position of the brightest spectral feature detected, and the color bar indicates the velocity of the spectral features with respect to a systemic velocity of −96.0 km/s. Details are given in the Proceedings of the International Astronomical Union Symposium 336.

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