The Widespread Occurrence of Water Vapor in the Circumstellar Envelopes of Carbon-Rich Asymptotic Giant Branch Stars: First Results From a Survey With Herschel/HIFI
Journal article, 2011
We report the preliminary results of a survey for water vapor in a sample of eight C stars with large mid-IR continuum fluxes: V384 Per, CIT 6, V Hya, Y CVn, IRAS 15194-5115, V Cyg, S Cep, and IRC+40540. This survey, performed using the HIFI instrument on board the Herschel Space Observatory, entailed observations of the lowest transitions of both ortho-and para-water: the 556.936 GHz 1(10)-1(01) and 1113.343 GHz 1(11)-0(00) transitions, respectively. Water vapor was unequivocally detected in all eight of the target stars. Prior to this survey, IRC+10216 was the only carbon-rich asymptotic giant branch (AGB) star from which thermal water emissions had been discovered, in that case with the use of the Submillimeter Wave Astronomy Satellite (SWAS). Our results indicate that IRC+10216 is not unusual, except insofar as its proximity to Earth leads to a large line flux that was detectable with SWAS. The water spectral line widths are typically similar to those of CO rotational lines, arguing against the vaporization of a Kuiper Belt analog being the general explanation for water vapor in carbon-rich AGB stars. There is no apparent correlation between the ratio of the integrated water line fluxes to the 6.3 mu m continuum flux-a ratio which measures the water outflow rate-and the total mass-loss rate for the stars in our sample.
outflow
winds
submillimeter: stars
spectra
mass-loss rates
v-hydrae
irc+10216
emission
chemistry
stars: abundances
lines
stars: AGB and post-AGB
discovery
circumstellar matter
Author
D. A. Neufeld
Johns Hopkins University
E. Gonzalez-Alfonso
University of Alcalá
G. J. Melnick
Harvard-Smithsonian Center for Astrophysics
R. Szczerba
Polish Academy of Sciences
M. Schmidt
Polish Academy of Sciences
L. Decin
KU Leuven
University of Amsterdam
J. Alcolea
Spanish National Observatory (OAN)
A. de Koter
University of Amsterdam
Sterrekundig Instituut Utrecht
Fredrik Schöier
Chalmers, Earth and Space Sciences, Onsala Space Observatory
V. Bujarrabal
Spanish National Observatory (OAN)
J. Cernicharo
Centro de Astrobiologia (CAB)
C. Dominik
Radboud University
University of Amsterdam
Kay Justtanont
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
A. P. Marston
European Space Astronomy Centre (ESAC)
K. Menten
Max Planck Society
Hans Olofsson
Chalmers, Earth and Space Sciences, Onsala Space Observatory
P. Planesas
Spanish National Observatory (OAN)
Atacama Large Millimeter-submillimeter Array (ALMA)
D. Teyssier
Centro de Astrobiologia (CAB)
Lbfm Waters
Netherlands Institute for Space Research (SRON)
University of Amsterdam
Astrophysical Journal Letters
2041-8205 (ISSN) 2041-8213 (eISSN)
Vol. 727 2 L29Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1088/2041-8205/727/2/L29