Water content and wind acceleration in the envelope around the oxygen-rich AGB star IK Tauri as seen by Herschel/HIFI
Artikel i vetenskaplig tidskrift, 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.

instrumentation: spectrographs

stars

isotopic abundances

submillimeter: stars

co

circumstellar envelopes

w-hya

evolved

circumstellar matter

giant branch stars

vapor

line emission

mass-loss history

carbon stars

stars: AGB and post-AGB

radiative transfer

line: profiles

Författare

L. Decin

Universiteit Van Amsterdam

KU Leuven

Kay Justtanont

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

Elvire De Beck

KU Leuven

R. Lombaert

KU Leuven

A. de Koter

Universiteit Van Amsterdam

Sterrekundig Instituut Utrecht

Lbfm Waters

Universiteit Van Amsterdam

A. P. Marston

European Space Astronomy Centre (ESA)

D. Teyssier

European Space Astronomy Centre (ESA)

Fredrik Schöier

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

V. Bujarrabal

J. Alcolea

J. Cernicharo

Centro de Astrobiologia (CAB)

C. Dominik

Radboud Universiteit

Universiteit Van Amsterdam

G. J. Melnick

Harvard-Smithsonian Center for Astrophysics

K. Menten

Max Planck-institutet

D. A. Neufeld

Johns Hopkins University

Hans Olofsson

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

P. Planesas

Atacama Large Millimeter-submillimeter Array (ALMA)

M. Schmidt

Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences

R. Szczerba

Nicolaus Copernicus Astronomical Center of the 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

CalTech

J. D. Gallego

Centro Astronomico de Yebes

M. C. Diez-Gonzalez

Centro Astronomico de Yebes

E. Caux

Université de Toulouse

Institut National des Sciences de l'Univers

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 521 1 Article Number: L4- L4

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/201015069