TY - JOUR
T1 - Water content and wind acceleration in the envelope around the oxygen-rich AGB star IK Tauri as seen by Herschel/HIFI
AU - Decin, L.
AU - Justtanont, K.
AU - De Beck, E.
AU - Lombaert, R.
AU - de Koter, A.
AU - Waters, L.B.F.M.
AU - Marston, A.P.
AU - Teyssier, D.
AU - Schöier, F. L.
AU - Bujarrabal, V.
AU - Alcolea, J.
AU - Cernicharo, J.
AU - Dominik, C.
AU - Melnick, G.
AU - Menten, K.
AU - Neufeld, D. A.
AU - Olofsson, H.
AU - Planesas, P.
AU - Schmidt, M.
AU - Szczerba, R.
AU - De Graauw, T.
AU - Helmich, F.
AU - Roelfsema, P.
AU - Dieleman, P.
AU - Morris, P.
AU - Gallego, J. D.
AU - Díez-González, M. C.
AU - Caux, E.
N1 - Herschel/HIFI: first science highlights
PY - 2010
Y1 - 2010
N2 - 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 H16
2 O and the rarer isotopologues H17
2 O and H18
2 O 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 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 12CO, 13CO,
28SiO, 29SiO, 30SiO, 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.
AB - 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 H16
2 O and the rarer isotopologues H17
2 O and H18
2 O 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 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 12CO, 13CO,
28SiO, 29SiO, 30SiO, 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.
KW - line: profiles
KW - radiative transfer
KW - instrumentation: spectrographs
KW - stars: AGB and post-AGB
KW - circumstellar matter
KW - submillimeter: stars
U2 - 10.1051/0004-6361/201015069
DO - 10.1051/0004-6361/201015069
M3 - Article
SN - 0004-6361
VL - 521
SP - L4/1-L4/7
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
IS - 1
ER -