scholarly journals Scattering by Dust in Planetary Nebulae: Polarization as a Diagnostic Tool

2003 ◽  
Vol 209 ◽  
pp. 321-322
Author(s):  
J. R. Walsh ◽  
L. Walsh
Keyword(s):  
Emission Line ◽  
Linear Polarization ◽  
Diagnostic Tool ◽  
Line Emission ◽  
Planetary Nebulae ◽  
Central Star ◽  
Line Profiles ◽  
Gaseous Emission ◽  
Atmospheric Scattering ◽  
Spatially Varying

There is a wealth of evidence for the presence of dust in PN from continuum and line emission in the IR, spatially varying extinction and ERE emission in the optical and strength of resonance lines in the UV. The dust emits strongly in the IR but in the UV-optical absorbs and scatters the radiation from the central star and the gaseous emission envelope. Linear polarization of PN light is thus an expected consequence of the presence of dust both within and outside the ionized region. Intrinsic scattering haloes of PN can be confused with local (telescope + atmospheric) scattering; polarimetry however allows the morphology of a dusty halo to be studied. Spectropolarimetry of emission line profiles allows the kinematics of the dust relative to the gaseous emission to be uniquely studied. Polarization contributes to understanding the scattering properties of the grains in PN and how they relate to those of the general ISM to which they will subsequently contribute.

scholarly journals Emission Line Profiles in the Planetary Nebulae IC 4593 and NGC 6153

1989 ◽  
Vol 131 ◽  
pp. 189-189
Author(s):  
D.P.K. Banerjee ◽  
B. G. Anandarao
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Planetary Nebulae ◽  
Central Star ◽  
Compact Objects ◽  
Emission Lines ◽  
Complex Structures ◽  
Line Profiles ◽  
Fabry Perot ◽  
Central Regions

The Planetary Nebulae IC 4593 and NGC 6153 are two rather compact objects not well studied. The nebula IC 4593 is about 12 arcsec in diameter and has a central star of Type 07 f; while the southern nebula NGC 6153 is about 22 arcsec in diameter and its central star is faint and of unknown spectral type. Using a high-resolution scanning Fabry-Pérot spectrometer we have made profile measurements of emission lines Hα λ6563 A, [O III] λ5007 A, and [N II] λ6584 A in the central regions of these two nebulae. We have found expansion velocities for IC 4593 of 40 km s−1 in [N II] and 16 km s−1 in [O III]. In the case of NGC 6153, we have obtained expansion velocities of 15 km s−1 in [N II] and 13 km s−1 in [O III] line. The profiles in Hα in both the nebulae dis not show a double peaked feature due to the larger thermal broadening. In the case of IC 4593, both [O III] and [N II] profiles showed complex structures. These results and their interpretation will be discussed.

scholarly journals Emission-Line Profiles in Planetary Nebulae

1968 ◽  
Vol 34 ◽  
pp. 267-269
Author(s):  
Donald E. Osterbrock
Keyword(s):  
Velocity Distribution ◽  
Emission Line ◽  
Observational Data ◽  
Planetary Nebulae ◽  
Line Profiles ◽  
Measured Velocity ◽  
Hydrodynamical Models ◽  
Internal Velocity ◽  
First Time

This research was undertaken with the idea of measuring as accurately as possible the internal-velocity distribution in planetary nebulae, in order to compare the observational measurements with hydrodynamical models of expanding nebulae. Much of the work was done in collaboration with J. S. Miller and D.W. Weedman. All the observational data were obtained photographically with the Coudé spectrograph of the 100-inch telescope at Mt. Wilson, using an image rotator, a 900 line/mm grating, and an F/5-2 camera, giving a dispersion of about 4 Å/mm in the blue and about 6 Å/mm in the red. The measured velocity resolution is approximately 5–6 km/sec. The data for five nebulae have been published (Osterbrock et al., 1966) while data for three more, NGC 2392, NGC 3242, and IC 418 are discussed here for the first time.

Emission-Line Profiles in Planetary Nebulae

1966 ◽  
Vol 145 ◽  
pp. 697 ◽  
Author(s):  
D. E. Osterbrock ◽  
J. S. Miller ◽  
D. W. Weedman
Keyword(s):  
Emission Line ◽  
Planetary Nebulae ◽  
Line Profiles

scholarly journals Interacting Nuclei in Distant Galaxies

1990 ◽  
Vol 124 ◽  
pp. 251-253
Author(s):  
Wei Zheng ◽  
Steven A. Grandi
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Outer Part ◽  
Line Emission ◽  
Galactic Nuclei ◽  
Balmer Line ◽  
Line Profiles ◽  
Double Peaks ◽  
Distant Galaxies

The interaction of galaxies not only occurs in galactic scales, but also may be linked to the binary cores in active galactic galaxies. The presence of a binary in the center of galaxies was suggested by Begelman, Blandford and Rees (1980). Gaskell (1983) suggests that supermassive binaries may account for the observed structure of emission line profiles such as double peaks displaced by a significant velocity difference. Collin-Souffrin, et al. (1986) argue that line emission may be formed in the outer part of an accretion disk. The resultant profile, as expected from rotational motion, would be very broad and often possess a double-horn shape. However, the emission line profiles in most active galactic nuclei do not share such a resemblance, and there are only two reported cases, 3C390.3 (Pérez et al. 1987) and Arp102B (Chen, Halpern and Filippenko 1989), in which the broad Balmer line profile may be of such a shape. Therefore, the assumption for accretion disk is to be verified with care.

scholarly journals The broad line emission from the AGN 3C 390.3: complex broad-line region and perturbation in accretion disk

2012 ◽  
Vol 8 (S290) ◽  
pp. 205-206
Author(s):  
Ilić Dragana ◽  
Luka Č. Popović ◽  
Alla I. Shapovalova ◽  
Alexander N. Burenkov ◽  
Vahram H. Chavushyan ◽  
...  
Keyword(s):  
Emission Line ◽  
Accretion Disk ◽  
Radio Galaxy ◽  
Dominant Role ◽  
Line Emission ◽  
Broad Line ◽  
Line Profiles ◽  
Broad Emission ◽  
Line Region ◽  
Present Part

AbstractFrom 13-years of the spectral optical monitoring of a well-known broad-line radio galaxy 3C 390.3 we concluded that the geometry of the broad emission-line region is complex, while still the main part of the emission is coming from the accretion disk. Here we present part of the analysis of the broad Hα and Hβ emission lines, which are showing highly variable double-peaked profiles during the monitoring period (1995-2007), with the aim to probe the accretion disk properties. The disk-like geometry plays a dominant role, but the variability of Hα and Hβ line profiles and intensities shows a presence of an additional emission-line region, that has a different nature for different periods, e.g. in one period the observed variation can be well modeled if one assumes changes in position and size of the emitting disk along the accretion disk.

scholarly journals IFU Spectroscopy of Southern Planetary Nebulae V: Low-Ionisation Structures

2017 ◽  
Vol 34 ◽  
Author(s):  
A. Ali ◽  
M. A. Dopita
Keyword(s):  
Emission Line ◽  
Planetary Nebulae ◽  
Central Star ◽  
Chemical Compositions ◽  
Physical Analysis ◽  
Type I ◽  
High Excitation ◽  
Chemical Abundances ◽  
Physical Conditions ◽  
Integral Field Spectroscopy

AbstractIn this fifth paper of the series, we examine the spectroscopy and morphology of four southern Galactic planetary nebulae Hen 2-141, NGC 5307, IC 2553, and PB 6 using new integral field spectroscopy data. The morphologies and ionisation structures of the sample are given as a set of emission-line maps. In addition, the physical conditions, chemical compositions, and kinematical characteristics of these objects are derived. The results show that PB 6 and Hen 2-141 are of very high excitation classes and IC 2553 and NGC 5307 are mid to high excitation objects. The elemental abundances reveal that PB 6 is of Type I, Hen 2-141 and IC 2553 are of Type IIa, and NGC 5307 is of Type IIb/III. The observations unveil the presence of well-defined low-ionisation structures or ‘knots’ in all objects. The diagnostic diagrams reveal that the excitation mechanism of these knots is probably by photoionisation of dense material by the nebular central stars. The physical analysis of six of these knots show no significant differences with their surrounding nebular gas, except their lower electron densities. In spite of the enhancement of the low-ionisation emission lines of these knots, their chemical abundances are nearly comparable to their surrounding nebulae, with the exception of perhaps slightly higher nitrogen abundances in the NGC 5307 knots. The integrated spectrum of IC 2553 reveals that nearly all key lines that have led researchers to characterise its central star as a weak-emission line star type are in fact of nebular origin.

scholarly journals A Catalog of Emission line profiles for Planetary Nebulae

2006 ◽  
Vol 2 (S234) ◽  
pp. 465 ◽  
Author(s):  
Christophe Morisset ◽  
Grazyna Stasinska
Keyword(s):  
Emission Line ◽  
Planetary Nebulae ◽  
Line Profiles
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