Recombination Line versus Forbidden Line Abundances in Planetary Nebulae

2005 ◽  
Vol 157 (2) ◽  
pp. 371-395 ◽  
Author(s):  
Mark Robertson‐Tessi ◽  
Donald R. Garnett
Keyword(s):  
Planetary Nebulae ◽  
Recombination Line

scholarly journals Determination of Element Abundances in Planetary Nebulae from Recombination Line Spectra

1993 ◽  
Vol 155 ◽  
pp. 573-573
Author(s):  
A.A. Nikitin ◽  
A.F. Kholtygin ◽  
A.A. Sapar ◽  
T. Kh. Feklistova
Keyword(s):  
Planetary Nebulae ◽  
Recombination Line ◽  
Element Abundances

Carbon, nitrogen and oxygen abundances have been found from the recombination lines for 63 planetary nebulae.

scholarly journals Millimetre observations of Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 266-266
Author(s):  
L.-Å. Nyman ◽  
G. Garay ◽  
H. E. Schwarz
Keyword(s):  
Planetary Nebulae ◽  
Recombination Line

We have observed a sample of 16 PNe of different morphological classes (from stellar to bipolar) in the mm-region, using the 15m Swedish-ESO Submillimetre Telescope (SEST). Continuum observations at 230 GHz were made with the SEST bolometer, and recombination line and continuum observations at 99 GHz (H40α) and 147 GHz (H35α) were made with SIS receivers.

scholarly journals A Survey of Recombination-line Abundances in Planetary Nebulae and H II Regions

2003 ◽  
Vol 209 ◽  
pp. 383-384 ◽  
Author(s):  
Y. G. Tsamis ◽  
M. J. Barlow ◽  
X.-W. Liu ◽  
I. J. Danziger
Keyword(s):  
Planetary Nebulae ◽  
Magellanic Cloud ◽  
H Ii Regions ◽  
Recombination Line ◽  
Large Aperture

We have derived C, N and O abundances, relative to H, using optical recombination lines (ORLs), for a number of galactic planetary nebulae and for three Magellanic Cloud PNe (LMC N66, N141, SMC N87) and compared them with the corresponding abundances derived from collisionally-excited lines (CELs). Our goal was to investigate the fact that PNe ORL abundances are in most cases larger than those obtained from CELs. Our scanning, long-slit observations were combined with large-aperture IUE, IRAS and ISO data to yield integrated abundances for more than half of our target objects.

scholarly journals Observations of 23 Planetary Nebulae at 408 MHz

1969 ◽  
Vol 22 (4) ◽  
pp. 545 ◽  
Author(s):  
AE Le Marne
Keyword(s):  
Planetary Nebulae ◽  
Radio Flux ◽  
Recombination Line ◽  
Hydrogen Recombination

Various observers (e.g. Slee and Orchiston 1965; Davies et al. 1967; Hughes 1967; Thompson and Colvin 1967; Thompson, Colvin, and Stanley 1967; Kaftan-Kassim 1968) have so far detected nearly 100 planetary nebulae a.t high radiofrequencies (~3 GHz). In this range, the nebulae have been shown to be optically thin, their spectra being almost flat. Wherever possible, the radio flux densities have been compared with hydrogen recombination line observations.

Element abundances in planetary nebulae from recombination line spectra

1994 ◽  
Vol 3 (1-2) ◽  
pp. 112-123
Author(s):  
A.A. Nikitin ◽  
A.F. Kholtygin ◽  
A. Sapar ◽  
T. Feklistova
Keyword(s):  
Planetary Nebulae ◽  
Recombination Line ◽  
Element Abundances

Detection of the H92 alpha Recombination Line toward the Very Compact Planetary Nebulae IC 5117 and HB 12

1995 ◽  
Vol 446 ◽  
pp. L39 ◽  
Author(s):  
Luis F. Miranda ◽  
Jose M. Torrelles ◽  
Carlos Eiroa
Keyword(s):  
Planetary Nebulae ◽  
Recombination Line

scholarly journals Close Binaries and the Abundance Discrepancy Problem in Planetary Nebulae

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 110
Author(s):  
R. Wesson ◽  
D. Jones ◽  
J. García-Rojas ◽  
H. Boffin ◽  
R. Corradi
Keyword(s):  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Central Star ◽  
Close Binaries ◽  
Problem Analysis ◽  
Recombination Line ◽  
Central Stars ◽  
Recent Establishment

Motivated by the recent establishment of a connection between central star binarity and extreme abundance discrepancies in planetary nebulae, we have carried out a spectroscopic survey targeting planetary nebula with binary central stars and previously unmeasured recombination line abundances. We have discovered seven new extreme abundance discrepancies, confirming that binarity is key to understanding the abundance discrepancy problem. Analysis of all 15 objects with a binary central star and a measured abundance discrepancy suggests a cut-off period of about 1.15 days, below which extreme abundance discrepancies are found.

scholarly journals Observations of near-infrared H2 emission in Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 221-221 ◽  
Author(s):  
Harriet L. Dinerstein ◽  
James Crawford
Keyword(s):  
Thermal Shock ◽  
Planetary Nebula ◽  
Surface Brightness ◽  
Near Infrared ◽  
Planetary Nebulae ◽  
Resolving Power ◽  
Emission Mechanism ◽  
Recombination Line ◽  
Line Flux ◽  
K Band

We report the results of a near-infrared (mostly K-band) spectroscopic survey of planetary nebulae at McDonald Observatory during the period 1986-1993. These observations were made with a grating spectrometer based on a 1 × 32-element InSb array. Most of the K-band observations were taken with spectral resolving power R = λ/Δλ = 600 in order to resolve the v=1-0 S(1) 2.121 μm H2 line from the adjacent recombination line of He I at 2.113 μm. We also simultaneously measured the strengths of H I Br γ and He II 2.189 μm. The typical limiting line flux detected in our 3.8″ beam was 1-3 × 10–14 erg cm–2 s–1, corresponding to a surface brightness of 3 × 10–5 to 1 × 10–4 erg cm–2 s–1 ster–1. An early result of this study was the first conclusive proof that the UV-pumping or “fluorescence” mechanism, rather than thermal (shock) excitation, is responsible for the H2 emission in a planetary nebula, Hubble 12 (Dinerstein et al. 1988, ApJ, 327, L27). This was also one of the first demonstrated cases of UV-pumped H2 emission in any astronomical source, and Hubble 12 has become a template for the study of this emission mechanism.

scholarly journals Recombination line abundances in the winds of the [WC] Wolf-Rayet stars

1997 ◽  
Vol 180 ◽  
pp. 112-113
Author(s):  
R. L. Kingsburgh ◽  
I. Dashevsky ◽  
M. J. Barlow
Keyword(s):  
Stellar Wind ◽  
Planetary Nebulae ◽  
Central Star ◽  
Emission Lines ◽  
Early Type ◽  
Recombination Line ◽  
Optical Spectrophotometry ◽  
Central Stars ◽  
Line Analysis

We present a preliminary abundance analysis, utilising recombination theory, for the [WC] Wolf-Rayet central stars of the planetary nebulae NGC 6751 and NGC 6905. This analysis is based on optical spectrophotometry of a sample of [WC] stars which show a strong O vi 3811, 34 å feature in emission. We have performed a recombination line analysis of stellar wind emission lines which are judged to be optically thin, in order to derive relative C, O and He abundances. We also present a comparison of the derived wind abundances with those of Population I WO stars. For the [WC 4] central star of NGC 6751, we have derived C/He = 0.35 and C/O = 4.2, by number. And for the [WC 3] central star of NGC 6905, we have derived C/He = 0.36 and C/O< 12. These surface abundances are comparable to the abundances that have been derived for early type [WC] stars via more complex NLTE modelling (e.g. Koesterke & Hamann 1996).

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