The Central Region of the Planetary Nebula A58

1993 ◽  
pp. 387-387 ◽  
Author(s):  
D. L. Pollacco ◽  
P. W. Hill ◽  
R. E. S. Clegg
Keyword(s):  
Central Region ◽  
Planetary Nebula

scholarly journals The multi-polar planetary nebula NGC 5189

2011 ◽  
Vol 7 (S283) ◽  
pp. 490-491
Author(s):  
Laurence Sabin ◽  
Roberto Vázquez ◽  
Jose A. Lopéz ◽  
Maria-Teresa García-Diaz
Keyword(s):  
High Resolution ◽  
Mass Loss ◽  
Optical Imaging ◽  
Central Region ◽  
Planetary Nebula ◽  
Spectroscopic Data ◽  
High Nitrogen ◽  
Central Source ◽  
North West ◽  
Nitrogen Levels

AbstractNGC 5189 is a particularly interesting planetary nebula (PN) displaying multiple bipolar structures. This type of morphology is generally attributed to multiple mass loss events believed to originate from a precessing central source. In order to better understand this, once dubbed chaotic PN, we have investigated optical imaging combined with low- and high- resolution spectroscopic data to dissect its components. The imaging reveals three and possibly four well defined bipolar lobes showing a misalignment with respect to the central torus, although sharing the same geometric center. The high nitrogen levels detected in the elongated filaments/condensations surrounding the nebula and at the torus location highlight the presence of low ionization structures as well as the possible occurrence of shocks in the areas perturbed by large dynamical motions. Finally the kinematical study indicates moderate expansion velocities (35 km.s−1 in the western lobe, 33 km.s−1 in the central region and 44 km.s−1 in the eastern lobe). We also notice the asymmetry of the [NII] distribution and the velocities inside NGC 5189 between its North-West and South-East components.

Molecular Hydrogen Emission from the Cometary Globules in the Helix Nebula (NGC 7293)

2003 ◽  
Vol 209 ◽  
pp. 275-276
Author(s):  
J. R. Walsh ◽  
N. Ageorges
Keyword(s):  
Central Region ◽  
Planetary Nebula ◽  
Molecular Hydrogen ◽  
Direct Evidence ◽  
Central Star ◽  
Small Distance ◽  
Ionization Front ◽  
The Sun ◽  
Hydrogen Emission ◽  
High Ionization

The discovery of many dense, dusty condensations in the Helix Nebula, NGC 7293, by Meaburn et al. (1992) was the first direct evidence of the real inhomogeneity of the medium of a planetary nebula. On account of the small distance of the Helix nebula from the Sun (~200pc), the knots (cometary globules) can be resolved from the ground and studied in detail from HST imaging (O'Dell & Handron, 1996). The condensations typically have a projected diameter of <2″ and hence sizes of <6 x 1015 cm. The condensations consist of a dusty core, visible as absorption against the background high ionization central region of the nebula for the foreground globules, and with a bow-shaped ionization front, strong in low ionization emission. The emission is displaced in the direction towards the central star, often with an outwardly-directed radial tail.

scholarly journals Evidence of Expansion in the Central Region of NGC 2346

1989 ◽  
Vol 131 ◽  
pp. 187-187
Author(s):  
D.P.K. Banerjee ◽  
B. G. Anandarao ◽  
J. N. Desai ◽  
S. K. Jain ◽  
D.C.V. Mallik
Keyword(s):  
High Resolution ◽  
Spectral Range ◽  
Central Region ◽  
Planetary Nebula ◽  
Signal To Noise Ratio ◽  
Emission Lines ◽  
Expansion Velocity ◽  
Signal To Noise ◽  
Central Spot ◽  
Fabry Perot

We present observations of the bipolar planetary nebula NGC 2346 carried out with the 1-m telescope at the Vainu Bappu Observatory in Kavalur, India using (1) a high resolution piezo-electric scanned Fabry-Pérot Spectrometer (with a velocity resolution of 10 km s−1) for line studies in the 6000 A - 7000 A spectral range and (2) a pressure scanned Fabry-Pérot spectrometer (with a velocity-resolution of 5 km s−1) in the green region. The nebula was observed in the H I 6563 A and [N II] 6583 A emission lines using a 15″ aperture and in the [O III] 5007 A line using an 8″ aperture centered on the bright central spot. A number of scans in each of these lines were co-added to improve the signal-to-noise ratio. The [O III] profile shows a well defined split between the blue and the red component, typical of an expanding shell. The [N II] profile does not show a well resolved split, although a pronounced suggestion of a split was observed in all the scans. The Hα profile was broad and asymmetric. The composite [O III] and [N II] profiles were decomposed into two individual Gaussians for obtaining the expansion velocity.

scholarly journals The Central Region of the Planetary Nebula A58

1993 ◽  
Vol 155 ◽  
pp. 387-387
Author(s):  
D.L. Pollacco ◽  
P.W. Hill ◽  
R.E.S. Clegg
Keyword(s):  
High Resolution ◽  
Central Region ◽  
Planetary Nebula ◽  
Emission Lines

We present images and high–resolution spectra of the hydrogen deficient knot at the centre of the old planetary nebula A58. The spectra confirm that this region contains essentially no hydrogen, as previously suspected. Emission lines from the knot are broad (FWHM ∼ 180 and 270 km/s for [NII] and [OIII] lines respectively) and are blue–shifted by ∼100 km/s relative to the systematic velocity.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

Access to effective ABA treatment in Ohio: Central region

2004 ◽  
Author(s):  
Christine Averill ◽  
Jacquie Wynn
Keyword(s):  
Central Region

The excavation of a disused military road at Buchlyvie, Central Region.

1994 ◽  
Vol 19 (1) ◽  
pp. 101-106 ◽  
Author(s):  
R. Page ◽  
C. Page
Keyword(s):  
Central Region ◽  
The Road

Summary Excavation of a road suspected to be Roman revealed a massive foundation surmounted by a flimsy upper road that had been little used except for cart traffic. The road was apparently part of the Stirling to Dumbarton military road, constructed between 1771 and 1780, one ofthe last military roads built in Scotland.

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