The rich far-infrared water vapour spectrum of W Hya

Article English OPEN
Barlow, M. J. ; Nguyen, Q. R. ; Truong, B. ; Cernicharo, J. ; Gonzalez-Alfonso, E. ; Liu, X. W. ; Cox, P. ; Sylvester, R. J. ; Clegg, P. E. ; Griffin, Matthew Joseph ; Swinyard, B. M. ; Unger, S. J. ; Baluteau, J. P. ; Caux, E. ; Cohen, M. ; Cohen, R. J. ; Emery, R. J. ; Fischer, J. ; Furniss, I. ; Glencross, W. M. ; Greenhouse, M. A. ; Gry, C. ; Joubert, M. ; Lim, T. ; Lorenzetti, D. ; Nisini, B. ; Omont, A. ; Orfei, R. ; Pequignot, D. ; Saraceno, P. ... view all 43 authors

We present an ISO Long Wavelength Spectrometer (LWS) grating spectrum of the oxygen-rich AGB star W Hya from 43-197μm. The spectrum is dominated by a forest of water vapour emission lines, confirming that H_2_O molecules are the dominant coolants of the winds of these stars. We have constructed an outflow model for the H_2_O spectrum of W Hya, which successfully matches the fluxes of most of the observed H_2_O lines, using an adopted wind temperature profile. These fits are sensitive to the mass loss rate, to the H_2_O abundance and to the inner radius of the H_2_O emitting region. The best fit parameters correspond to a mass loss rate of 6x10^-7^Msun_/yr, inner and outer radii for the emitting region of 1.5x10^14^ and 1x10^16^cm, and a H_2_O/H_2_ abundance of 8x10^-4^ for r <=4.5x10^14^cm and 3x10^-4^ at large radii. A decrease of the H_2_O/H_2_ abundance in the outer envelope is consistent with the predictions of photochemical models. The availability for the first time of observations of the line fluxes from the dominant coolant species should enable improved models of the wind temperature distribution to be produced.
  • References (1)

    Bujarrabal V., Gomez-Gonzalez J., Planesas P. 1989, A&A, 219, 256 Cahn J. H., Elitzur M. 1979, ApJ, 231, 124 Chapman J. M., et al. 1994, MNRAS, 268, 475 Chen W., Neufeld D. A. 1995, ApJL, 453, L99 Clegg P. E., et al. 1996, this volume Deguchi S, Rieu N-Q. 1990, ApJL, 360, L27 Elitzur M., et al. 1976, ApJ, 205, 384, 1976 Goldreich P., Scoville N. 1976, ApJ, 205, 144 Green S., Maluendes S., McLean A.D. 1993, ApJS, 85, 181 Huggins P., Glassgold A. E. 1982, AJ, 87, 1828 Kessler M. F., et al. 1996, this volume Lewis B. M., 1990, AJ, 99, 710 Liu X.-W., et al. 1996, this volume Loup C., Forveille T., Omont A., Paul J. F. 1993, A&AS, 99, 490 Menten K. M., Melnick G. J. 1991, ApJ, 377, 647 Swinyard B. M., et al. 1996, this volume Zuckerman B., Dyck H. M. 1986, ApJ, 304, 394

  • Metrics
    views in OpenAIRE
    views in local repository
    downloads in local repository

    The information is available from the following content providers:

    From Number Of Views Number Of Downloads
    Online Research @ Cardiff - IRUS-UK 0 14
Share - Bookmark