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 Title: Astronomical Masers: Polarization Properties Of 22-ghz Water And 6.7-ghz Methanol Masers. Author(s): Surcis, Gabriele Contributor(s): van Langevelde, Huib Jan; Vlemmings, Wouter H.T. Subject(s): Astronomy Abstract: By observing the astronomical masers in the Milky Way we can determine for instance high-accurate distances of the hosting Galactic sources (e.g., Galactic star-forming regions) and the kinematic of the gas where the masers arise (e.g., the kinematic of Keplerian accretion disks and outflows in massive star-forming regions). In addition, the bright and narrow spectral line emissions of water and methanol masers are ideal for measuring the Zeeman splitting as well as for determining the orientation of the magnetic field in 3-dimensions around massive young stellar objects (YSOs). Therefore, water and methanol maser species can help us to answer several crucial questions about massive star-formation. For instance, one of the most debated question is whether magnetic fields are important in the formation of high-mass stars ($M>8~\rm{M_{sun}}$). The main difficulty in answering this question is related to the fast evolution of the high-mass stars that makes the massive YSOs rare. Furthermore, they are typically found at fairly large distance. Hence, it is very difficult to measure the magnetic fields at distances $<100$ Astronomical Units from the central protostar by using dust polarized emissions. But fortunately, the direct measurement of magnetic fields at small scale (10-100~Astronomical Units) around massive YSOs is possible by observing the polarized emission of masers.\\ \indent In my oral contribution, besides showing the polarization properties of 22-GHz water and 6.7-GHz methanol masers, I will show our most interesting results about the determination of the orientation and of the strength of magnetic fields around massive YSOs. We have also started a systematic study for determining if there exists a real alignment between magnetic fields and the large scale outflows that are launched from the central protostar, which is important to constrain future simulations. Furthermore, we are involved in laboratory and modelling efforts to calibrate the magnitude of the Zeeman effect for methanol masers. Issue Date: 2014-06-16 Publisher: International Symposium on Molecular Spectroscopy Citation Info: Surcis, G.; van Langevelde, H.J.; Vlemmings, W.H. ASTRONOMICAL MASERS: POLARIZATION PROPERTIES OF 22-GHZ WATER AND 6.7-GHZ METHANOL MASERS.. Proceedings of the International Symposium on Molecular Spectroscopy, Urbana, IL, June 16-21, 2014. DOI: 10.15278/isms.2014.MF08 Genre: CONFERENCE PAPER/PRESENTATION Type: Text Language: English URI: http://hdl.handle.net/2142/50964 DOI: https://doi.org/10.15278/isms.2014.MF08 Rights Information: Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/ Date Available in IDEALS: 2014-09-172015-04-14
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