Ultraviolet spectra of planetary nebulae - VII. The abundance of carbon in the very low excitation nebula He 2-131

Adams, S.; Seaton, M. J.

doi:10.1093/mnras/200.1.7p

Cited by 9 publications

(7 citation statements)

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“…Numerous studies of the UV spectrum of IC 418 have been made with the IUE. See Harrington et al (1980); Clavel, Flower, and Seaton (1981); Boggess, Feibelman, and McCracken (1981); and Adams and Seaton (1982). Improved reduction techniques for re-evaluation of the nebular emis- sions, are now available at the Goddard Regional Data Analysis Facility (RDAF).…”

Section: Spectroscopic Observationsmentioning

confidence: 99%

“…Why is IC 418 interesting? First of all it is a bright, C-enhanced (Adams and Seaton 1982), object with a welldefined ring structure. It is a young PN, perhaps less than a thousand years old (Phillips, Riera, and Mampaso 1990) in which a relatively small H II region is surrounded by a vast envelope of neutral hydrogen.…”

Section: Introductionmentioning

confidence: 99%

“…] 05 a 27 m 28?3, S=-12 4L 48" (2000) 1 = 215-2, b=-24-2 Diameter of main (slightly elliptical ring) =12" Diameter of outer, neutral shell of H i gas= 180" (Taylor et al 1989) V(exp) = 12 km sec -1 [N n] log F(H/?) = -9.58±0.02 ergs cm" 2 s -1 ra(dust)/ra(gas)=6X 10 -4 (Hoare 1990) C/O ratio -1.3 (Adams and Seaton 1982) Central star: BD -12°1172, HD 35914, B=10.0, V=10.17 Distance: estimates range from 330 pc (Acker 1978) to 2000 pc (Mendez et al 1988).…”

Section: Introductionmentioning

confidence: 99%

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The spectrum of the planetary nebula IC 418

Hyung

Aller

Feibelman

1994

PASP

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A detailed high-spectral-resolution study of the spectrum of IC 418 is made for the region 3650 to 10050 Â, using the Hamilton echelle spectrograph of Lick Observatory, and of the UV spectral region with archival International Ultraviolet Explorer (IUE) data. From high-resolution images in both the near-and mid-infrared, Hora et al. (1993) showed that IC 418 probably has a compact shell interior to the detached, well-known, main shell emission. If one assumes a black body or Hubeny (or standard LTE) model atmosphere energy distribution, it does not appear possible to construct a fully satisfactory nebula model that will simultaneously represent the Hß flux, the [O m]5007/H/3 ratio, and the scale of this planetary nebula (PN). Fortunately, IUE and IR data supply information on ions in addition to those optically observed so that the chemical composition can be reasonably well established by summing over concentrations of observed ions. In spite of the fact that IC 418 is carbon rich in sense of having a C/O ratio exceeding the solar value, it is a "metal-poor" object. Possibly it resembles IC 4997 but in a more advanced evolutionary phase. The central star is variable and has a strong wind.

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Section: Spectroscopic Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The spectrum of the planetary nebula IC 418

Hyung

Aller

Feibelman

1994

PASP

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“…Hen 2-131: This object's IUE spectra were briefly discussed by Adams & Seaton (1982). However, attention was given to the determination of the C/O ratio in the nebula, not to the central star.…”

Section: Line Identifications and Measurementsmentioning

confidence: 99%

“…A few studies in the UV including some WELSs can be found in the literature. However, they often include stars of different spectral classes (e.g., Feibelman 2000) and/or are focused on the determination of nebular properties (e.g., Adams & Seaton 1982;Pottasch et al 2005), without special attention to the WELSs and their evolutionary state. Motivated by this fact and considering the open questions described above, we investigate in this paper the UV spectra of all WELSs with available IUE (International Ultraviolet Explorer) data.…”

Section: Introductionmentioning

confidence: 99%

The Ultraviolet Spectra of the Weak Emission Line Central Stars of Planetary Nebulae

Marcolino

Araújo

et al. 2007

Astron J

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The UV spectra of all ''weak emission line central stars of planetary nebulae'' (WELSs) with available IUE data are presented and discussed. We performed line identifications and equivalent-width and flux measurements for several features in the spectra. We found that the WELSs can be divided into three different groups regarding their UV spectra: (1) strong P Cygni profiles (mainly in C iv k1549), (2) weak P Cygni features, and (3) absence of P Cygni profiles. The last group encompasses stars with a featureless UV spectrum or with intense emission lines and a weak continuum, which are most likely of nebular origin. We have measured wind terminal velocities for all objects presenting P Cygni profiles in N v k1238 and/or C iv k1549. The results obtained were compared to the UV data of the two prototype stars of the [WC]ÀPG 1159 class, namely, A30 and A78. For WELSs presenting P Cygni features, most of the terminal velocities fall in the range of $1000-1500 km s À1 , while [WC]ÀPG 1159 stars possess much higher values, of $3000 km s À1 . The [WC]ÀPG 1159 stars are characterized by intense, simultaneous P Cygni emissions in the $1150-2000 8 interval of N v k1238, O v k1371, and C iv k1549. In contrast, we found that O v k1371 is very weak or absent in the WELS spectra. On the basis of the UV spectra alone, our findings indicate that [WC]ÀPG 1159 stars are distinct from the WELSs, contrary to previous claims in the literature.

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Some Recent Results from UV Observations

Seaton¹

1983

Planetary Nebulae

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Ultraviolet spectra of planetary nebulae - VII. The abundance of carbon in the very low excitation nebula He 2-131

Cited by 9 publications

References 0 publications

The spectrum of the planetary nebula IC 418

The spectrum of the planetary nebula IC 418

The Ultraviolet Spectra of the Weak Emission Line Central Stars of Planetary Nebulae

Some Recent Results from UV Observations

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