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Water content and wind acceleration in the envelope around the oxygen-rich AGB star IK Tauri as seen by Herschel/HIFI

Decin, L. and Morris, P. (2010) Water content and wind acceleration in the envelope around the oxygen-rich AGB star IK Tauri as seen by Herschel/HIFI. Astronomy and Astrophysics, 521 . Art. No. L4. ISSN 0004-6361.

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During their asymptotic giant branch evolution, low-mass stars lose a significant fraction of their mass through an intense wind, enriching the interstellar medium with products of nucleosynthesis. We observed the nearby oxygen-rich asymptotic giant branch star IK Tau using the highresolution HIFI spectrometer onboard Herschel. We report on the first detection of H^(16)_2O and the rarer isotopologues H^(17)_2O and H^(18)_2O in both the ortho and para states. We deduce a total water content (relative to molecular hydrogen) of 6.6 × 10^(−5), and an ortho-to-para ratio of 3:1. These results are consistent with the formation of H_2O in thermodynamical chemical equilibrium at photospheric temperatures, and does not require pulsationally induced non-equilibrium chemistry, vaporization of icy bodies or grain surface reactions. High-excitation lines of ^(12)CO, ^(13)CO, ^(28)SiO, ^(29)SiO, ^(30)SiO, HCN, and SO have also been detected. From the observed line widths, the acceleration region in the inner wind zone can be characterized, and we show that the wind acceleration is slower than hitherto anticipated.

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Additional Information:© 2010 ESO. Received 28 May 2010, Accepted 16 June 2010, Published online 01 October 2010. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Appendices (pages 6 and 7) are only available in electronic form at HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada and the United States under the leadership of SRON Netherlands Institute for Space Research, Groningen, The Netherlands and with major contributions from Germany, France and the US. Consortium members are: Canada: CSA, U. Waterloo; France: CESR, LAB, LERMA, IRAM; Germany: KOSMA, MPIfR, MPS; Ireland, NUI Maynooth; Italy: ASI, IFSI-INAF, Osservatorio Astrofisico di Arcetri- INAF; Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio Astronómico Nacional (IGN), Centro de Astrobiología (CSIC-INTA); Sweden: Chalmers University of Technology – MC2, RSS & GARD; Onsala Space Observatory; Swedish National Space Board, Stockholm University – Stockholm Observatory; Switzerland: ETH Zurich, FHNW; USA: Caltech, JPL, NHSC. HCSS / HSpot / HIPE is a joint development by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS and SPIRE consortia. LD acknowledges financial support from the Fund for Scientific Research - Flanders (FWO). This work has been partially supported by the Spanish MICINN, program CONSOLIDER INGENIO 2010, grant ASTROMOL (CSD2009-00038). R.Sz. and M.Sch. acknowledge support from grant N 203 393334 from Polish MNiSW. J.C. thanks funding from MICINN, grant AYA2009-07304. This research was performed, in part, through a JPL contract funded by the National Aeronautics and Space Administration.
Funding AgencyGrant Number
Fonds Voor Wetenschappelijk Onderzoek (FWO) (Belgium)UNSPECIFIED
Ministerio de Ciencia e Innovación (MCINN) (Spain)CSD2009-00038
Ministerstwo Nauki i Szkolnictwa Wyższego (Poland)N 203 393334
Ministerio de Ciencia e Innovación (MCINN) (Spain)AYA2009-07304
Subject Keywords:line: profiles – radiative transfer – instrumentation: spectrographs – stars: AGB and post-AGB – circumstellar matter – submillimeter: stars
Record Number:CaltechAUTHORS:20101222-150429993
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Official Citation:Water content and wind acceleration in the envelope around the oxygen-rich AGB star IK Tauri as seen by Herschel/HIFI L. Decin, K. Justtanont, E. De Beck, R. Lombaert, A. de Koter, L. B. F. M. Waters, A. P. Marston, D. Teyssier, F. L. Schöier, V. Bujarrabal, J. Alcolea, J. Cernicharo, C. Dominik, G. Melnick, K. Menten, D. A. Neufeld, H. Olofsson, P. Planesas, M. Schmidt, R. Szczerba, T. de Graauw, F. Helmich, P. Roelfsema, P. Dieleman, P. Morris, J. D. Gallego, M. C. Díez-González and E. Caux A&A 521 L4 (2010) DOI: 10.1051/0004-6361/201015069
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21506
Deposited By: Benjamin Perez
Deposited On:23 Dec 2010 17:05
Last Modified:03 Oct 2019 02:25

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