scholarly journals Flux Ratio [Ne v] 14.3/24.3 as a Test of Collision Strengths

2004 ◽  
Vol 217 ◽  
pp. 190-191
Author(s):  
R.H. Rubin
Keyword(s):  
Electron Density ◽  
Flux Ratio ◽  
Planetary Nebulae ◽  
Atomic Data ◽  
Line Flux ◽  
Astronomical Data ◽  
Data Collision

From ISO [Ne v] 14.3/24.3 μm line flux ratios, we find that 10 out of 20 planetary nebulae (PNs) have measured ratios below the low-electron density (Ne) theoretical predicted limit. Such astronomical data serve to provide important tests of atomic data, collision strengths in this case. In principle, well-calibrated measurements of the [Ne v] 14.3/24.3 flux ratio could improve upon the existing atomic data.

scholarly journals Atomic data and the density structures of planetary nebulae

2021 ◽  
Author(s):  
Leticia Juan de Dios ◽  
Mónica Rodríguez
Keyword(s):  
Electron Density ◽  
Planetary Nebulae ◽  
Atomic Data ◽  
The Impact

Abstract We study the density structures of planetary nebulae implied by four diagnostics that sample different regions within the nebulae: [S ii] λ6716/λ6731, [O ii] λ3726/λ3729, [Cl iii] λ5518/λ5538, and [Ar iv] λ4711/λ4740. We use a sample of 46 objects with deep spectra that allow the calculation of the electron density from these four diagnostics, and explore the impact that different atomic data have on the results. We compare the observational results with those obtained from photoionization models characterized by three different density structures. We conclude that the atomic data used in the calculations of electron density fully determine the density structures that are derived for the objects. We illustrate this by selecting three combinations of atomic data that lead to observational results that are compatible with each of the three different density structures explored with the models.

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.

scholarly journals Birthrate of PN

1983 ◽  
Vol 103 ◽  
pp. 424-425 ◽  
Author(s):  
D.C.V. Mallik
Keyword(s):  
Electron Density ◽  
Surface Density ◽  
Planetary Nebulae ◽  
Number Density ◽  
Continuum Radiation ◽  
Complete Catalogue

Recent observations of planetary nebulae have called into question the Shklovsky method of measuring distances. For those planetaries for which independent distance and electron density determinations are available, it is found that the ionized mass and the radius are linearly correlated (Maciel and Pottasch, 1980) and also that the ionized masses increase with decreasing electron density (Pottasch, 1981). These relations imply that the nebulae are optically thick in Ly continuum radiation and the distances based on the Shklovsky method are overestimates. Using an empirically determined mass-radius relationship Maciel and Pottasch have obtained new distances for the nebulae in the catalogue of Milne and Aller (1975). We have used the more complete catalogue of Cahn and Kaler (1971) to obtain distances corrected for possible variations in the ionized mass and have compiled a new list of local planetaries. We obtain a surface density of 15 ± 3 kpc−2 and a planar number density of 44 ± 4 kpc−3.

scholarly journals Prediction of H α and [O iii] emission line galaxy number counts for future galaxy redshift surveys

2019 ◽  
Vol 490 (3) ◽  
pp. 3667-3678 ◽  
Author(s):  
Zhongxu Zhai ◽  
Andrew Benson ◽  
Yun Wang ◽  
Gustavo Yepes ◽  
Chia-Hsun Chuang
Keyword(s):  
Emission Line ◽  
Galaxy Formation ◽  
Luminosity Function ◽  
Large Scale ◽  
High Redshift ◽  
Flux Ratio ◽  
Formation Model ◽  
Line Flux ◽  
Emission Line Galaxies ◽  
Number Counts

ABSTRACT We perform a simulation with Galacticus, a semi-analytical galaxy formation model, to predict the number counts of H α and [O iii] emitting galaxies. With a state-of-the-art N-body simulation, UNIT, we first calibrate Galacticus with the current observation of H α luminosity function. The resulting model coupled with a dust attenuation model, can reproduce the current observations, including the H α luminosity function from HiZELS and number density from WISP. We extrapolate the model prediction to higher redshift and the result is found to be consistent with previous investigations. We then use the same galaxy formation model to predict the number counts for [O iii] emitting galaxies. The result provides further validation of our galaxy formation model and dust model. We present number counts of H α and [O iii] emission line galaxies for three different line flux limits: 5 × 10−17erg s−1 cm−2, 1 × 10−16 erg s−1 cm−2 (6.5σ nominal depth for WFIRST GRS), and 2 × 10−16 erg s−1 cm−2 (3.5σ depth of Euclid GRS). At redshift 2 < z < 3, our model predicts that WFIRST can observe hundreds of [O iii] emission line galaxies per square degree with a line flux limit of 1 × 10−16 erg s−1 cm−2. This will provide accurate measurement of large-scale structure to probe dark energy over a huge cosmic volume to an unprecedented high redshift. Finally, we compare the flux ratio of H α/[O iii] within the redshift range of 0 < z < 3. Our results show the known trend of increasing H α/[O iii] flux ratio with H α flux at low redshift, which becomes a weaker trend at higher redshifts.

scholarly journals Ionic Abundances of S III, O IV and NeV from Infrared Observations of Fine Structure Lines in eight Planetary Nebulae

1983 ◽  
Vol 103 ◽  
pp. 512-512
Author(s):  
M.A. Shure ◽  
T.L. Herter ◽  
J.R. Houck ◽  
D.A. Briotta ◽  
W.J. Forrest ◽  
...  
Keyword(s):  
Fine Structure ◽  
Electron Temperature ◽  
Planetary Nebulae ◽  
Optical Observations ◽  
Constant Density ◽  
Line Flux ◽  
Infrared Observations ◽  
Infrared Measurements ◽  
Fine Structure Lines

The Kuiper Airborne Observatory has been used to make measurements of the infrared forbidden lines of (SIII) 18.72μm, (NeV) 24.28μm and (OIV) 25.87μm in eight planetary nebulae. In all cases the beam was larger than the emitting region. The observed line fluxes are used to determine ionic abundances under the assumption of constant density throughout the relevant volume as determined by optical observations. In some cases the NeV near UV lines are used in conjunction with the infrared measurements to determine the electron temperature in the NeV emission regions. The (SIII) 33.47μm line can be used with the (SIII) 18.72μm line flux to characterize the clumping within the nebulae.

scholarly journals MBPT Results for Δn=0 Electric Dipole Transitions

1993 ◽  
Vol 155 ◽  
pp. 96-96
Author(s):  
G. Gaigalas ◽  
R. Kisielius ◽  
G. Merkelis ◽  
Z. Rudzikas ◽  
M. Vilkas
Keyword(s):  
Electric Dipole ◽  
Planetary Nebulae ◽  
Atomic Data ◽  
Atomic Lines

To identify spectra of Planetary Nebulae which usually have many atomic lines one needs very accurate theoretical atomic data.

scholarly journals Emission-Line Fluxes of Northern Planetary Nebulae

2015 ◽  
Vol 32 ◽  
Author(s):  
N. Aksaker ◽  
S. K. Yerli ◽  
Ü Kızıloğlu ◽  
B. Atalay
Keyword(s):  
Emission Line ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Supernova Remnants ◽  
Planetary Nebulae ◽  
Line Flux ◽  
Chemical Abundances ◽  
Flux Measurements ◽  
First Time

AbstractWe present long slit spectrophotometric emission line fluxes of bright and extended (< 5 arcsec in diameter) planetary nebulae (PNe), selected from a catalogue with suitable equatorial coordinates for northern hemisphere. In total, 17 planetary nebulae have been chosen and observed in 2008–2010. To measure absolute fluxes, broad slit sizes, ranging from 3.5 to 7.5 arcsec were used and thus equivalent widths (EW) of all observable emission line fluxes were also calculated. Among 17 planetary nebulae observed, line flux measurements of 12 of them were made for the first time. This work also aims to extend the sky coverage of emission line flux standards in northern hemisphere (52 planetary nebulae in southern hemisphere; 6 planetary nebulae in northern hemisphere). Electron temperatures and densities, and chemical abundances of these planetary nebulae were also calculated in this work. These data are expected to lead the photometric or spectrometric further work for absolute emission line flux measurements needed for H ii regions, supernova remnants etc.

scholarly journals Improved Neutron-Capture Element Abundances in Planetary Nebulae

2009 ◽  
Vol 26 (3) ◽  
pp. 339-344 ◽  
Author(s):  
N. C. Sterling ◽  
H. L. Dinerstein ◽  
S. Hwang ◽  
S. Redfield ◽  
A. Aguilar ◽  
...  
Keyword(s):  
Cross Sections ◽  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
Rate Coefficients ◽  
Atomic Data ◽  
Agb Stars ◽  
Iron Species ◽  
Element Abundances ◽  
Ionization Balance ◽  
Initial Results

AbstractSpectroscopy of planetary nebulae (PNe) provides the means to investigate s-process enrichments of neutron(n)-capture elements that cannot be detected in Asymptotic Giant Branch (AGB) stars. However, accurate abundance determinations of these elements present a challenge. Corrections for unobserved ions can be large and uncertain, since in many PNe only one ion of a given n-capture element has been detected. Furthermore, the atomic data governing the ionization balance of these species are not well-determined, inhibiting the derivation of accurate ionization corrections. We present initial results of a program that addresses these challenges. Deep high-resolution optical spectroscopy of ∼20 PNe has been performed to detect emission lines from trans-iron species including Se, Br, Kr, Rb and Xe. The optical spectral region provides access to multiple ions of these elements, which reduces the magnitude and importance of uncertainties in the ionization corrections. In addition, experimental and theoretical efforts are providing determinations of the photoionization cross sections and recombination rate coefficients of Se, Kr and Xe ions. These new atomic data will make it possible to derive robust ionization corrections for these elements. Together, our observational and atomic data results will enable n-capture element abundances to be determined with unprecedented accuracy in ionized nebulae.

scholarly journals Atomic Data and Neutron-Capture Element Abundances in Planetary Nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 74-81
Author(s):  
N. C. Sterling
Keyword(s):  
Neutron Capture ◽  
Milky Way ◽  
Planetary Nebulae ◽  
Atomic Data ◽  
Experimental Investigations ◽  
Agb Stars ◽  
Intermediate Mass ◽  
Element Abundances ◽  
Nearby Galaxies

AbstractNeutron(n)-capture elements are produced by s-process nucleosynthesis in low- and intermediate-mass AGB stars, and therefore can be enriched in planetary nebulae (PNe). In the last ten years, n-capture elements have been detected in more than 100 PNe in the Milky Way and nearby galaxies. In some objects, several different n-capture elements have been detected, providing valuable constraints to models of AGB nucleosynthesis and evolution. These detections have motivated theoretical and experimental investigations of the atomic data needed to derive accurate n-capture element abundances. In this review, I discuss the methods and results of these atomic data studies, and their application to abundance determinations in PNe.

Planetary Nebulae: Doublets give Electron Density

Nature ◽  
1970 ◽  
Vol 225 (5238) ◽  
pp. 1099-1100
Author(s):  
Our Astronomy Correspondent
Keyword(s):  
Electron Density ◽  
Planetary Nebulae
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