Rapidly evolving episodic outflow in IRAS 18113-2503: Clues to the ejection mechanism of the fastest water fountain

Water fountains are evolved stars showing early stages of collimated mass-loss during transition from the asymptotic giant branch, providing valuable insight into the formation of asymmetric planetary nebulae. We report the results of multi-epoch VLBI observations, which determine the spatial and th...

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Detalles Bibliográficos
Autores: Orosz, G., Gómez, José F., Imai, H., Tafoya, D., Torrelles, José M., Burns, R.A., Frau, P., Guerrero, Martín A., Miranda, Luis F., Pérez-Torres, Miguel A., Ramos-Larios, G., Rizzo, José Ricardo, Suárez, O., Uscanga, Lucero
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2019
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/179358
Acceso en línea:http://hdl.handle.net/10261/179358
Access Level:acceso abierto
Palabra clave:Astrometry
Masers
Stars: AGB and post-AGB
Stars: jets
Stars: individual (IRAS 18113-2503)
Binaries: general
Descripción
Sumario:Water fountains are evolved stars showing early stages of collimated mass-loss during transition from the asymptotic giant branch, providing valuable insight into the formation of asymmetric planetary nebulae. We report the results of multi-epoch VLBI observations, which determine the spatial and three-dimensional kinematic structure of HO masers associated with the water fountain IRAS 18113-2503. Themasers trace three pairs of high-velocity (~150-300 km s) bipolar bow shocks on a scale of 0.>18 (~2000 au). The expansion velocities of the bow shocks exhibit an exponential decrease as a function of distance from the central star, which can be explained by an episodic, jet-driven outflow decelerating due to drag forces in a circumstellar envelope. Using our model, we estimate an initial ejection velocity ~840 km s, a period for the ejections ~10 yr, with the youngest being ~12 yr old, and an average envelope density within the HO maser region n ≈10 cm. We hypothesize that IRAS 18113-2503 hosts a binary central star with a separation of ~10 au, revealing novel clues about the launching mechanisms of high-velocity collimated outflows in water fountains.© 2018 The Author(s).

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