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 High-resolution emission line profiles in blue luminous stars

1989 ◽  
Vol 113 ◽  
pp. 279-280
Author(s):  
Rino Bandiera ◽  
Paola Focardi ◽  
Aldo Altamore ◽  
Corinne Rossi ◽  
Otmar Stahl
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
High Velocity ◽  
Large Scale ◽  
Velocity Fields ◽  
Emission Lines ◽  
Line Profiles ◽  
High Luminosity ◽  
Stellar Envelopes ◽  
Η Car

Emission lines are often observed in high luminosity stars and provide evidence of the presence of extended stellar envelopes. Ha is the most frequently observed across the H-R diagram, but lines of Hel or Fell are also found in emission in these stars. They could be used as diagnostics of the structure of their outer atmospheres and winds. High resolution (1/dl ~ 105) high S/N profiles of Ha and Hel 5876 in the galactic LBVs η Car, AG and HR Car, and in the LMC star S22 have been obtained with the ESO CAT-CES during 1984-87, and are described in Figs.1-5. We find that these stars show a large variety of profiles with narrow and broad emissions, wide or multiple blue-shifted absorptions. The profiles are largely variable. Once, a kind of inverse P Cyg profile was observed in HR Car (Fig.4). These results indicate the presence of large scale phenomena and high velocity fields which are dramatically variable in time. Continuous HIRES monitoring of these stars is urgently needed.

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 High-Resolution Emission-Line Spectroscopy of Be Stars: Comparison of Hα and Weak Emission Lines

1987 ◽  
Vol 92 ◽  
pp. 208-210
Author(s):  
Reinhard W. Hanuschik
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Rotational Velocity ◽  
Outer Radius ◽  
Emission Lines ◽  
Be Stars ◽  
Line Profiles ◽  
Component Structure ◽  
Double Peak Structure ◽  
Disk Component

AbstractFor a number of bright southern Be stars, high-resolution, high S/N spectroscopy has been performed for Hα, Si II λ6371 and four Fe II emission lines. With the exception of four stars, both Hα and weak emission line profiles exhibit resolved double-peak structure. Peak separation increases with stellar projected rotational velocity. In many cases, Hα profiles (but not Fe II lines) show resolved fine-structure (inflections in the flanks) indicating a two-component structure of the disk. Envelope models with arbitrary density and rotational velocity laws have been fitted to the Fe II line profiles with satisfactory results. It is found that the innermost Hα disk component also emits the Fe II lines and has an average outer radius of 5 r*; density falls off as r-l.5 or more rapidly. The outer disk component emits the faint and narrow secondary component of Hα lines with average outer radius 20 r*. The envelopes of the four stars with a strong, dominating single peak both in Hα and Fe II either are dominated by strong radial motions or, more likely, have elliptical disk-like structure.

scholarly journals Hybrid 3-D Spectrophotometry of Emission-Line Nebulae at Ohio State

1995 ◽  
Vol 149 ◽  
pp. 167-171
Author(s):  
Richard W. Pogge ◽  
Nancy Joanne Lame
Keyword(s):  
Emission Line ◽  
Planetary Nebulae ◽  
Hii Regions ◽  
Ohio State University ◽  
State University ◽  
Considerable Success ◽  
Fabry Perot ◽  
The Ohio State University ◽  
Scientific Results ◽  
Narrowband Filter

AbstractA program of 3-D spectrophotometry of emission nebulae being carried out at the Ohio State University will be described. We have had considerable success combining Fabry-Perot imaging, long-slit spectroscopy, and narrowband filter imaging into a hybrid 3-D spectroscopic approach that we have used to obtain detailed spectrophotometric maps of the density, temperature, extinction, and ionization in HII regions and Planetary Nebulae. The centerpiece instrument of this effort, the OSU Imaging Fabry-Perot Spectrograph (IFPS), will be described, and scientific results illustrative of our work will be presented.

scholarly journals Kinematic Structure and Chemical Composition of the Double Shell PN NGC 3242

1989 ◽  
Vol 131 ◽  
pp. 200-200
Author(s):  
K. C. Sahu ◽  
S. R. Pottasch ◽  
B. G. Anandarao ◽  
J. N. Desai
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Outer Shell ◽  
Expansion Velocity ◽  
Kinematic Structure ◽  
Line Profiles ◽  
Kinematic Study ◽  
Fabry Perot

Kinematic study of the multiple shell PN NGC 3242 was carried out by obtaining Hα and [O III] line profiles at 9 positions of the nebula using a high-resolution (R ≅ 50,000) Fabry-Pérot spectrometer. The positions cover both the bright inner shell and the faint outer shell. It is shown here that the two apparently continuous shells are kinematically separate: the faint outer shell was ejected ∼ 5000 years earlier and has less expansion velocity than the bright inner shell.

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.

scholarly journals Forbidden line diagnostics of photoevaporative disc winds

2020 ◽  
Vol 496 (3) ◽  
pp. 2932-2945 ◽  
Author(s):  
G Ballabio ◽  
R D Alexander ◽  
C J Clarke
Keyword(s):  
Sound Speed ◽  
Central Star ◽  
High Energy ◽  
Emission Lines ◽  
Limiting Factor ◽  
Line Profiles ◽  
Gas Temperature ◽  
Characteristic Emission ◽  
Extreme Uv ◽  
High Sound

ABSTRACT Photoevaporation driven by high-energy radiation from the central star plays an important role in the evolution of protoplanetary discs. Photoevaporative winds have been unambiguously detected through blue-shifted emission lines, but their detailed properties remain uncertain. Here we present a new empirical approach to make observational predictions of these thermal winds, seeking to fill the gap between theory and observations. We use a self-similar model of an isothermal wind to compute line profiles of several characteristic emission lines (in particular the [Ne ii] line at 12.81 μm, and optical forbidden lines such as [O i] 6300 Å and [S ii] 4068/4076 Å), studying how the lines are affected by parameters such as the gas temperature, disc inclinations, and density profile. Our model successfully reproduces blue-shifted lines with $v_{\rm peak} \lesssim 10$ km s−1, which decrease with increasing disc inclination. The line widths increase with increasing disc inclinations and range from $\Delta v\sim 15\text{ to }30$ km s−1. The predicted blue-shifts are mostly sensitive to the gas sound speed (and therefore the temperature). The observed [Ne ii] line profiles are consistent with a thermal wind and point towards a relatively high sound speed, as expected for extreme-UV photoevaporation. However, the observed [O i] line profiles require lower temperatures, as expected in X-ray photoevaporation, and show a wider scatter that is difficult to reconcile with a single wind model; it seems likely that these lines trace different components of a multiphase wind. We also note that the spectral resolution of current observations remains an important limiting factor in these studies, and that higher resolution spectra are required if emission lines are to further our understanding of protoplanetary disc winds.

Arp 70: an interacting galaxy with extreme outflows

2020 ◽  
Vol 493 (1) ◽  
pp. 1434-1446
Author(s):  
A Camps-Fariña ◽  
J E Beckman ◽  
J Font ◽  
I del Moral-Castro ◽  
S F Sanchez ◽  
...  
Keyword(s):  
Emission Line ◽  
The Other ◽  
Spectral Signature ◽  
Main Peak ◽  
Physical Parameters ◽  
Line Profiles ◽  
Public Repository ◽  
Line Region ◽  
Fabry Perot ◽  
H Ii Region

ABSTRACT We analysed a Fabry–Pérot (FP) cube of the interacting pair of galaxies Arp 70, which was obtained from the CeSAM public repository of FP data. On the larger galaxy Arp 70b, we detected the spectral signature of two different outflows, one located in the centre and the other associated with a giant H ii region in the arm region. The central outflow is especially prominent, with the flux of the secondary peaks in the emission-line profiles due to the outflowing gas being similar to that of the main peak. We used an archive fibre spectrum from SDSS to confirm this detection in H α as well as in the [N ii] line and, in addition, to perform diagnostics on the nature of the ionization. The emission at the centre is consistent with a low-ionization nuclear emission-line region and a weak active galactic nucleus. Using the spatial distribution of the profiles in the FP cube, we estimated the shape of the outflow which is consistent with two cones of expanding material, one approaching and the other receding from us, and used this to estimate the physical parameters of the outflow, finding energies of order 1057 erg and masses of order 108 M⊙. On the giant H ii region, we found a very large expanding superbubble with a diameter of ∼5 kpc. The bubble has an energy of order 1054 erg and a mass of about 4 × 107 M⊙. We discuss the possible origins for both of these features and whether they could be associated with the interaction between the galaxies.

scholarly journals Modeling hydrogen-deficient Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 235-235
Author(s):  
J. P. Harrington ◽  
K. J. Borkowski ◽  
Z. I. Tsvetanov
Keyword(s):  
Planetary Nebulae ◽  
Central Star ◽  
Central Regions

Hydrogen-deficient planetary nebulae have central regions devoid of hydrogen. (See Harrington 1996 for a review of these nebulae.) They are characterized by exceptionally strong collisionally excited lines of [O III] and [Ne III], but relatively weak or undetected recombination lines of He or other elements. Such nebulae cannot be modeled successfully unless we include some source of heating in addition to photoionization by the central star.

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