Water content and wind acceleration in the envelope around the oxygen-rich AGB star IK Tauri as seen by Herschel/HIFI
Journal article, 2010
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 high-resolution HIFI spectrometer onboard Herschel. We report on the first detection of (H2O)-O-16 and the rarer isotopologues (H2O)-O-17 and (H2O)-O-18 in both the ortho and para states. We deduce a total water content (relative to molecular hydrogen) of 6.6 x 10(-5), and an ortho-to-para ratio of 3:1. These results are consistent with the formation of H2O 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 (CO)-C-12, (CO)-C-13, (SiO)-Si-28, (SiO)-Si-29, (SiO)-Si-30, 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.
submillimeter: stars
mass-loss history
radiative transfer
giant branch stars
w-hya
circumstellar matter
stars
instrumentation: spectrographs
isotopic abundances
line emission
stars: AGB and post-AGB
evolved
circumstellar envelopes
line: profiles
carbon stars
co
vapor
Author
L. Decin
KU Leuven
University of Amsterdam
Kay Justtanont
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
Elvire De Beck
KU Leuven
R. Lombaert
KU Leuven
A. de Koter
Sterrekundig Instituut Utrecht
University of Amsterdam
Lbfm Waters
University of Amsterdam
A. P. Marston
European Space Agency (ESA)
D. Teyssier
European Space Agency (ESA)
Fredrik Schöier
Chalmers, Earth and Space Sciences, Onsala Space Observatory
V. Bujarrabal
J. Alcolea
J. Cernicharo
Centro de Astrobiologia (CAB)
C. Dominik
University of Amsterdam
Radboud University
G. J. Melnick
Harvard-Smithsonian Center for Astrophysics
K. Menten
Max Planck Society
D. A. Neufeld
Johns Hopkins University
Hans Olofsson
Chalmers, Earth and Space Sciences, Onsala Space Observatory
P. Planesas
Atacama Large Millimeter-submillimeter Array (ALMA)
M. Schmidt
Polish Academy of Sciences
R. Szczerba
Polish Academy of Sciences
T. de Graauw
Atacama Large Millimeter-submillimeter Array (ALMA)
F. Helmich
Netherlands Institute for Space Research (SRON)
P. Roelfsema
Netherlands Institute for Space Research (SRON)
P. Dieleman
Netherlands Institute for Space Research (SRON)
P. Morris
California Institute of Technology (Caltech)
J. D. Gallego
Yebes Observatory
M. C. Diez-Gonzalez
Yebes Observatory
E. Caux
University of Toulouse
Institut National des Sciences de l'Univers
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 521 1 Article Number: L4- L4Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201015069