The ionizing radiation field of NGC 4388 and its relation to the extranuclear emission-line regions

1992 ◽  
Vol 386 ◽  
pp. 59 ◽  
Author(s):  
Luis Colina
Keyword(s):  
Ionizing Radiation ◽  
Emission Line ◽  
Radiation Field

scholarly journals The Ionization of Planetary Nebulae

1968 ◽  
Vol 34 ◽  
pp. 190-204 ◽  
Author(s):  
Robert E. Williams
Keyword(s):  
Ionizing Radiation ◽  
Emission Line ◽  
Radiation Field ◽  
Planetary Nebulae ◽  
Model Atmosphere ◽  
Evolutionary Sequence ◽  
Lyman Continuum ◽  
The Mean ◽  
Central Stars

The ionization of the most abundant elements in planetary nebulae has been determined for a number of models of nebulae at different epochs in their expansion. The values used for the temperatures and radii of the central stars and the sizes and densities of the shells have come from Seaton's evolutionary sequence. The ionizing radiation field has been taken from model atmosphere calculations of the central stars by Gebbie and Seaton, and Böhm and Deinzer. Emission-line fluxes have been calculated for the models and compared with observations of planetary nebulae by O'Dell, Osterbrock's group, and Aller and his collaborators. Results indicate that the central stars have strong He+ Lyman continuum excesses, similar to those predicted by Gebbie and Seaton. The mean abundance determinations for the nebulae made by Aller are confirmed, with the exception of nitrogen, which appears to be 3 or 4 times more abundant than his value. It is also seen that the electron temperatures of the nebulae are higher than previous theoretical determinations, providing better agreement with empirically derived values.

scholarly journals Nebular abundances in galaxies: Beware of biases

2009 ◽  
Vol 5 (S262) ◽  
pp. 93-96 ◽  
Author(s):  
Grażyna Stasińska
Keyword(s):  
Ionizing Radiation ◽  
Emission Line ◽  
Structural Properties ◽  
Radiation Field ◽  
Dwarf Galaxies ◽  
Strong Line ◽  
Compact Galaxies

AbstractThe derivation of nebular abundances in galaxies using strong line methods is simple and quick. Various indices have been designed and calibrated for this purpose, and they are widely used. However, abundances derived with such methods may be significantly biased, if the objects under study have different structural properties (hardness of the ionizing radiation field, morphology of the nebulae) than those used to calibrate the methods. Special caution is required when comparing the metallicities of different samples, like, for example, blue compact galaxies and other emission line dwarf galaxies, or samples at different redshifts.

scholarly journals Constraints on the production and escape of ionizing radiation from the emission-lines of metal-poor star-forming galaxies

2019 ◽  
Vol 15 (S352) ◽  
pp. 121-122
Author(s):  
A. Plat ◽  
S. Charlot ◽  
G. Bruzual ◽  
A. Feltre ◽  
A. Vidal-Garca ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Emission Line ◽  
Active Galactic Nuclei ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Radiative Shocks ◽  
Metal Poor Star

AbstractTo understand how the nature of the ionizing sources and the leakage of ionizing photons in high-redshift galaxies can be constrained from their emission-line spectra, we compare emission-line models of star-forming galaxies including leakage of ionizing radiation, active galactic nuclei (AGN) and radiative shocks, with observations of galaxies at various redshifts with properties expected to approach those of primeval galaxies.

scholarly journals Spectrophotometric studies of Planetary Nebulae with [WR] central stars

1997 ◽  
Vol 180 ◽  
pp. 269-269
Author(s):  
M. Peña ◽  
G. Stasińska ◽  
C. Esteban ◽  
R. Kingsburgh ◽  
L. Koesterke ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Radiation Field ◽  
Planetary Nebulae ◽  
Model Atmosphere ◽  
The Other ◽  
Self Consistent ◽  
First Results ◽  
Photoionization Model ◽  
Central Stars

We present the first results of a project on PNe with [WR] nuclei whose aim is twofold. One is to search for possible spatial abundance variations inside the nebula. The other is to check whether, for each object, one can build a self-consistent photoionization model (with the code PHOTO, Stasińska 1990, A&AS, 83, 501) using, as an input, the ionizing radiation field from an expanding model atmosphere reproducing the observed stellar lines of He, C and O (Koesterke et al., these proceedings).

scholarly journals The Nature of GQ Mus As Depicted From Photoionization Models of the Shell

1996 ◽  
Vol 158 ◽  
pp. 305-306
Author(s):  
D. Péquignot ◽  
C. Morisset
Keyword(s):  
Ionizing Radiation ◽  
Emission Line ◽  
Effective Temperature ◽  
Time Variation ◽  
Line Spectrum ◽  
Thermal Source ◽  
Model Study ◽  
Emission Line Spectrum ◽  
Photoionization Model

Consequences of a detailed photoionization model study of the shell ejected by Nova Mus 1983 (GQ Mus) are presented for the period from early 1983 to 1990 (Morisset & Péquignot 1996).The drastic time variation of the emission line spectrum, including the transition from a nebular to a coronal stage in 1986, can be quantitatively understood in terms of a smooth evolution of both the expanding shell and the hot thermal source. This transition is due to a decrease of the shell density with time, and not to an increase of the source effective temperature.The model shell comprises two components so that not all directions become optically thin to ionizing radiation simultaneously. The range of density and geometrical thickness of the emitting material is of the order of a factor 2.

Damage to proteins due to the direct action of ionizing radiation

1993 ◽  
Vol 26 (1) ◽  
pp. 27-48 ◽  
Author(s):  
E. S. Kempner
Keyword(s):  
Ionizing Radiation ◽  
Radiation Field ◽  
Direct Action ◽  
Short Period ◽  
Irreversible Effects

Proteins exposed to ionizing radiation suffer both reversible and irreversible effects. Reversible effects are defined as those which disappear in a short period of time after the removal of the radiation field and without further treatment of the sample. Irreversible effects are those which cause a permanent alteration in the structure of a protein.

Ignition of Hydrogen-Oxygen-Diluent Mixtures in an Ionizing Radiation Field

1992 ◽  
Vol 83 (1-3) ◽  
pp. 145-159
Author(s):  
R. K. KUMAR ◽  
G. W. KOROLL ◽  
W. A. DEWIT ◽  
E. L. HALLIN ◽  
D. M. SKOPIK ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Radiation Field

scholarly journals Shaping bipolar and elliptical Planetary Nebulae: Rotation and magnetic field

1997 ◽  
Vol 180 ◽  
pp. 226-226 ◽  
Author(s):  
Guillermo García-Segura ◽  
Norbert Langer ◽  
Michał Różyczka ◽  
Mordechai-Mark Mac Low ◽  
José Franco
Keyword(s):  
Magnetic Field ◽  
Ionizing Radiation ◽  
Radiation Field ◽  
Binary Systems ◽  
Planetary Nebulae ◽  
Stellar Rotation ◽  
Central Source ◽  
Formation And Evolution

We present hydrodynamical and magnetohydronynamical simulations for the formation and evolution of bipolar and elliptical planetary nebulae with two interacting winds. The models are performed under the hypothesis of a single central source, i.e. binary systems are not considered and a single initial wind function is used in our calculations. We explore various relevant parameters, including the effects of stellar rotation, ionizing radiation field and stellar magnetic field, and a catalogue of resulting shapes is generated.

scholarly journals Gauging Metallicity of Diffuse Gas under an Uncertain Ionizing Radiation Field

2017 ◽  
Vol 842 (2) ◽  
pp. L19 ◽  
Author(s):  
Hsiao-Wen Chen ◽  
Sean D. Johnson ◽  
Fakhri S. Zahedy ◽  
Michael Rauch ◽  
John S. Mulchaey
Keyword(s):  
Ionizing Radiation ◽  
Radiation Field

scholarly journals Far-infrared spectroscopy of Planetary Nebulae with the KAO

1997 ◽  
Vol 180 ◽  
pp. 278-278
Author(s):  
R. H. Rubin ◽  
S.W.J. Colgan ◽  
M.R. Haas ◽  
S. D. Lord ◽  
J. P. Simpson
Keyword(s):  
Infrared Spectroscopy ◽  
Ionizing Radiation ◽  
Radiation Field ◽  
Electron Density ◽  
Flux Ratio ◽  
Planetary Nebulae ◽  
Far Infrared ◽  
Far Infrared Spectroscopy ◽  
Ionic Ratio ◽  
Ngc 7027

We present new far-infrared line observations of the planetary nebulae (PNs) NGC 7027, NGC 7009, NGC 6210, NGC 6543, and IC 4997 obtained with the Kuiper Airborne Observatory (KAO). The bulk of our data are for NGC 7027 and NGC 7009, including [Ne V] 24 μm, [O IV] 26 μm, [O III] (52, 88μm), and [Nm] 57 μm. Our data for [O III] (52, 88) and [N III] 57 in NGC 7027 represent the first measurements of these lines in this source. The large [O III] 52/88 flux ratio implies an electron density (cm–3) of log Ne[O III] = 4.19, the largest Ne ever inferred from these lines. We derive N++/O++ = 0.394±0.062 for NGC 7027 and 0.179±0.043 for NGC 6210. We are able to infer the O+3/O++ ionic ratio from our data. As gauged by this ionic ratio, NGC 7027 is substantially higher ionization than is NGC 7009 – consistent with our observation that the former produces copious [Ne V] emission while the latter does not. These data help characterize the stellar ionizing radiation field.

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