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J/MNRAS/368/1959    Chemical abundances for Hf 2-2           (Liu+, 2006)
Chemical abundances for Hf 2-2, a planetary nebula with the strongest-known
heavy-element recombination lines.
    Liu X.-W., Barlow M.J., Zhang Y., Bastin R.J., Storey P.J.
   <Mon. Not. R. Astron. Soc., 368, 1959-1970 (2006)>
   =2006MNRAS.368.1959L
ADC_Keywords: Planetary nebulae ; Abundances

Keywords: ISM: abundances - planetary nebulae: individual: Hf 2-2


Abstract:
    We present high-quality optical spectroscopic observations of the
    planetary nebula (PN) Hf 2-2. The spectrum exhibits many prominent
    optical recombination lines (ORLs) from heavy-element ions. Analysis
    of the H I and He I recombination spectrum yields an electron
    temperature of ∼900K, a factor of 10 lower than given by the
    collisionally excited [O III] forbidden lines. The ionic abundances of
    heavy elements relative to hydrogen derived from ORLs are about a
    factor of 70 higher than those deduced from collisionally excited
    lines (CELs) from the same ions, the largest abundance discrepancy
    factor (adf) ever measured for a PN.

Description:
    Hf 2-2 was observed on three photometric nights in June 2001 with the
    Boller & Chivens long-slit spectrograph mounted on the European
    Southern Observatory (ESO) 1.52-m telescope.
    Two wavelength regions were observed. The blue region was observed
    with a 2400-lines/mm holographic grating, which yielded a dispersion
    of 32Å/mm, or ∼0.5Å/pix. Some vignetting was observed, in
    particular on the blue side of this large format CCD, which limited
    the useful wavelength range to 3540-4800Å. A slitwidth of 2arcsec
    was used for maximum spectral resolution. In addition, in order to
    obtain magnitudes for the central star, two spectra with slitwidths of
    4 and 8arcsec were also obtained.
Objects:
    -----------------------------------------------
       RA   (2000)   DE      Designation(s)
    -----------------------------------------------
    18 32 30.9   -28 43 20   PN Hf 2-2 = Hen 2-407
    -----------------------------------------------

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table2.dat       101      119   Observed relative line fluxes, on a scale
                             where Hβ=100
table4.dat        61       71   Electron temperatures and ionic and elemental
                             abundances deduced from recombination lines and
                             continuum


Byte-by-byte Description of file: table2.dat

   Bytes Format Units   Label     Explanations

   1- 14  A14   ---     Line      Identification of line observed
  17- 20  I4    0.1nm   lambda    Wavelength
  22- 27  F6.3  ---    f(lambda)  Reddening law (Howard, 1983MNRAS.203..301H)
  29- 34  F6.2  ---     FluxO2    Observed flux 2 arcsec slitwidth (1)
  36- 39  F4.2  ---     e_FluxO2  ? rms uncertainty on FluxO2 (1)
  41- 46  F6.2  ---     FluxO4    ? Observed flux 4 arcsec slitwidth (1)
  48- 51  F4.2  ---     e_FluxO4  ? rms uncertainty on FluxO4 (1)
  53- 58  F6.2  ---     FluxO8    ? Observed flux 8 arcsec slitwidth (1)
  60- 64  F5.2  ---     e_FluxO8  ? rms uncertainty on FluxO8 (1)
  66- 71  F6.2  ---     FluxD2    Dereddened flux 2 arcsec slitwidth (1)
  73- 76  F4.2  ---     e_FluxD2  ? rms uncertainty on FluxD2 (1)
  78- 83  F6.2  ---     FluxD4    ? Dereddened flux 4 arcsec slitwidth (1)
  85- 88  F4.2  ---     e_FluxD4  ? rms uncertainty on FluxD4 (1)
  90- 95  F6.2  ---     FluxD8    ? Dereddened flux 8 arcsec slitwidth (1)
  97-101  F5.2  ---     e_FluxD8  ? rms uncertainty on FluxD8 (1)

Note (1): Fluxes on a scale where F(Hβ)=100.



Byte-by-byte Description of file: table4.dat

   Bytes Format Units   Label     Explanations

   1- 12  A12   ---     Param     Parameter name (e.g. El/H+)
  14- 28  A15   ---     Line      Line (or Adopted) Diagnostic (1)
  30- 37  E8.5  ---     A2        ? Abundance in 2 arcsec slitwidth spectra
      41  A1    ---     l_A4      Limit flag on A4
  42- 49  E8.2  ---     A4        ? Abundance in 4 arcsec slitwidth spectra
  54- 61  E8.2  ---     A8        ? Abundance in 8 arcsec slitwidth spectra

Note (1): Adopted abundances:
     He/H = 0.104
     C/H  = 4.27E-3
     N/H  = 3.29E-3
     O/H  = 8.62E-3
     Ne/H = 3.28E-3
     for effectives temperatures:
     -------------------------------------------------------------
     Line            Teff (K)    Teff (K)    Teff (K)
                     slitwidth2" slitwidth4" slitwidth8"
     -------------------------------------------------------------
     BJ/H 11            930        875         910
     He I(5876/4471)    940       <550         720
     He I(6678/4471)   1170                   1000
     O II(4089/4649)    630        630         630
     -------------------------------------------------------------


History:
    From electronic version of the journal
(End)                                      Patricia Vannier [CDS]    15-Dec-2006