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 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 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