scholarly journals The Edinburgh/AAO/Strasbourg Catalogue of Galactic Planetary Nebulae

2003 ◽  
Vol 209 ◽  
pp. 41-41 ◽  
Author(s):  
Q. A. Parker ◽  
M. Hartley ◽  
D. Russeil ◽  
A. Acker ◽  
F. Ochsenbein ◽  
...  
Keyword(s):  
Galactic Plane ◽  
Angular Size ◽  
Planetary Nebulae ◽  
Depth Resolution ◽  
Central Star ◽  
Isolation And Identification ◽  
Large Numbers ◽  
Low Surface Brightness ◽  
Bulge Region ◽  
Version 2.0

We report on version 1.0 of the Edinburgh/AAO/Strasbourg catalogue of new and possible Planetary Nebulae (PN) distributed via cdrom at this meeting. We provide accurate positions, designations, images and other descriptive parameters for the PN. In future releases this will be supplemented by inclusion of spectra and related material such as line ratios, velocities etc.The 900+ PN have been discovered solely from visual scrutiny of narrow-band exposures taken for the AAO/UKST H-alpha survey of the Southern Galactic Plane. Most have classic PN-type morphologies (i.e. bi-polar, rings, shells or ovals). SuperCOSMOS data will soon supersede our visual scanning but it proved an effective preliminary technique to identify candidate PN on the basis of morphology, isolation and identification as an H-alpha nebulosity. We already have confirmatory spectroscopy for ~ 700 objects. Much of our new sample are of very low surface brightness, with no obvious central star, and so have remained undetected in previous surveys. They are revealed here due to the excellent depth, resolution, coverage and uniformity of the H-alpha survey. Many PN are also well extended. The average angular size is 51″ with the median of 27″ but examples extend to several arcminutes. This may indicate many are in a highly evolved state where the central star has faded from easy optical detection and the nebula itself is dissipating into the ambient ISM. Large numbers of candidate PN have also been found in the Galactic Bulge region, most of which have been confirmed via UKST FLAIR/6dF MOS spectroscopy (Parker et al, in preparation and these proceedings).By version 2.0 (release in 2002) we will have doubled the number of Galactic PN accrued from all sources over the last 75 years. This new catalogue should have a profound impact on many aspects of PN research.

scholarly journals An imaging and spectroscopic survey of the Abell Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 287-287
Author(s):  
N. A. Walton ◽  
J. R. Walsh ◽  
G. Dudziak
Keyword(s):  
White Dwarf ◽  
Surface Brightness ◽  
Planetary Nebulae ◽  
Central Star ◽  
Large Size ◽  
Low Surface Brightness ◽  
Thermal Pulses ◽  
Central Stars

The Abell catalogue of planetary nebulae (PN) are distinguished by their large size, low surface brightness and generally faint central stars. They are thought to be old PN approaching the White Dwarf cooling track. A number have evidence for late thermal pulses (H-poor ejecta near the central star, e.g. A78) and binary central stars.

scholarly journals A Rich New Vein of Planetary Nebulae From the AAO/UKST Hα Survey

2003 ◽  
Vol 209 ◽  
pp. 25-32
Author(s):  
Q. A. Parker ◽  
M. Hartley ◽  
D. Russeil ◽  
A. Acker ◽  
D. H. Morgan ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Galactic Plane ◽  
Planetary Nebulae ◽  
Lower Surface ◽  
Large Numbers

We report on an unprecedented source of Planetary Nebulae (PN) discovered from AAO/UKST Hα survey images of the Southern Galactic Plane. A pristine region of PN discovery space is being sampled due to the excellent depth, coverage, resolution and uniformity of the Hα survey. Large numbers of new PN are being found (~1000 so far). They are typically more evolved, obscurred and of lower surface brightness than in most other surveys. The doubling of known PN should have a significant impact on many aspects of PN research.

scholarly journals The Binary Central Star of Hf 38

2016 ◽  
Vol 12 (S323) ◽  
pp. 382-383
Author(s):  
Helen Barker
Keyword(s):  
Planetary Nebula ◽  
Galactic Plane ◽  
Planetary Nebulae ◽  
Central Star ◽  
Using Data ◽  
The Impact ◽  
Initial Results ◽  
Central Stars

AbstractDespite years of effort, the impact of central star binarity on planetary nebula formation and shaping remains unclear. This is hampered by the fact that detecting central star binarity is inherently difficult, and requires very precise observations. The fraction of planetary nebulae with binary central stars therefore remains elusive. This work presents initial results of central star analysis using data from the VST Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+). The true central star of PN Hf 38 has been revealed, and it exhibits a 0.465±0.334 i band magnitude excess, indicative of a M0V companion.

scholarly journals Two New Planetary Nebulae and an AGN in the Galactic Plane

1999 ◽  
Vol 16 (2) ◽  
pp. 134-138 ◽  
Author(s):  
S. H. Beer ◽  
A. E. Vaughan
Keyword(s):  
Radio Emission ◽  
Planetary Nebula ◽  
Galactic Plane ◽  
Angular Size ◽  
Planetary Nebulae ◽  
Optical Spectra ◽  
Radio Flux ◽  
Low Resolution ◽  
5 Ghz

AbstractA search for planetary nebulae was carried out using candidates selected by their infrared colours and 5 GHz radio emission. One new planetary nebula was identified on the basis of its small angular size, strong [O iii] emission and infrared colours. Another object, known as the possible planetary nebula Wray 16–28, is similarly identified as a planetary nebula. An undiscovered AGN was also found, and is classed as a Seyfert 2 galaxy on the basis of its strong O iii emission, linewidths of ∼500 km s−1, and 5 GHz radio flux. Low-resolution optical spectra are presented and distance estimates discussed.

scholarly journals HST Observations of the Nuclei of EGB 6 (0950+139) and Abell 58 (V605 Aql)

1993 ◽  
Vol 155 ◽  
pp. 499-499
Author(s):  
Howard E. Bond ◽  
Michael G. Meakes ◽  
James W. Liebert ◽  
Alvio Renzini
Keyword(s):  
Emission Line ◽  
Surface Brightness ◽  
Hubble Space Telescope ◽  
Planetary Nebulae ◽  
Central Star ◽  
Space Telescope ◽  
Faint Object ◽  
Low Surface Brightness ◽  
Central Stars

This paper deals with the central stars of two large, low-surface-brightness planetary nebulae: V605 Aquilae, central star of Abell 58, and 0950+139, central star of EGB 6. Both of these nuclei are associated with compact emission-line nebulosities, which are unresolved from the ground. We obtained images with the Faint Object Camera (FOC) on the Hubble Space Telescope of both objects, in order to determine the nature of the compact nebulae.

scholarly journals Planetary Nebula Evolution Traced by Distance-Independent Parameters

1993 ◽  
Vol 155 ◽  
pp. 480-480
Author(s):  
C.Y. Zhang ◽  
S. Kwok
Keyword(s):  
Physical Properties ◽  
Mass Distribution ◽  
Planetary Nebula ◽  
Strong Support ◽  
Planetary Nebulae ◽  
Central Star ◽  
Evolution Model ◽  
The Core ◽  
Independent Parameters ◽  
Central Stars

Making use of the results from recent infrared and radio surveys of planetary nebulae, we have selected 431 nebulae to form a sample where a number of distance-independent parameters (e.g., Tb, Td, I60μm and IRE) can be constructed. In addition, we also made use of other distance-independent parameters ne and T∗ where recent measurements are available. We have investigated the relationships among these parameters in the context of a coupled evolution model of the nebula and the central star. We find that most of the observed data in fact lie within the area covered by the model tracks, therefore lending strong support to the correctness of the model. Most interestingly, we find that the evolutionary tracks for nebulae with central stars of different core masses can be separated in a Tb-T∗ plane. This implies that the core masses and ages of the central stars can be determined completely independent of distance assumptions. The core masses and ages have been obtained for 302 central stars with previously determined central-star temperatures. We find that the mass distribution of the central stars strongly peaks at 0.6 M⊙, with 66% of the sample having masses <0.64 MM⊙. The luminosities of the central stars are then derived from their positions in the HR diagram according to their core masses and central star temperatures. If this method of mass (and luminosity) determination turns out to be accurate, we can bypass the extremely unreliable estimates for distances, and will be able to derive other physical properties of planetary nebulae.

scholarly journals The Remarkable Evolution of the Post-Agb Star FG SGE

1998 ◽  
Vol 11 (1) ◽  
pp. 363-363
Author(s):  
Johanna Jurcsik ◽  
Benjamin Montesinos
Keyword(s):  
Time Scales ◽  
Effective Temperature ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Central Star ◽  
Evolutionary Models ◽  
Single Star ◽  
Line Intensities ◽  
Evolutionary Changes ◽  
Evolutionary Studies

FG Sagittae is one of the most important key objects of post-AGB stellar evolutionary studies. As a consequence of a final helium shell flash, this unique variable has shown real evolutionary changes on human time scales during this century. The observational history was reviewed in comparison with predictions from evolutionary models. The central star of the old planetary nebula (Hel-5) evolved from left to right in the HR diagram, going in just hundred years from the hot region of exciting sources of planetary nebulae to the cool red supergiant domain just before our eyes becoming a newly-born post-AGB star. The effective temperature of the star was around 50,000 K at the beginning of this century, and the last estimates in the late 1980s give 5,000-6,500 K. Recent spectroscopic observations obtained by Ingemar Lundström show definite changes in the nebular line intensities. This fact undoubtedly rules out the possibility that, instead of FG Sge, a hidden hot object would be the true central star of the nebula. Consequently, the observed evolutionary changes are connected with the evolution of a single star.

scholarly journals Chemical Enrichment and Central Star Properties

1993 ◽  
Vol 155 ◽  
pp. 572-572
Author(s):  
C.Y. Zhang
Keyword(s):  
Planetary Nebulae ◽  
Central Star ◽  
Agb Stars ◽  
Physical Processes ◽  
Chemical Abundances ◽  
Core Mass ◽  
Chemical Enrichment ◽  
The Core ◽  
Stellar Temperature ◽  
Independent Parameters

We have selected a sample of planetary nebulae, for which the core masses are determined using distance-independent parameters (Zhang and Kwok 1992). The chemical abundances of He, N, O, and C are taken from the literature for them. Relationships of the ratios of He/H, N/O, and C/O with various stellar parameters of planetary nebulae (PN), such as the core mass, the mass of the core plus the ionized nebular gas, the stellar age and temperature, are examined. It is found that the N/O increases with increasing mass, while the C/O first increases and then decreases with the core mass. No strong correlation seems to exist between the He/H and the core mass. A correlation of the N/O and He/H with the stellar temperature exists. The current dredge-up theory for the progenitor AGB stars cannot satisfactorily account for these patterns of chemical enrichment in PN. Furthermore, the correlations of the N/O and He/H with the stellar age and temperature indicate that besides the dredge-ups in the RG and AGB stages, physical processes that happen in the planetary nebula stage may also play a role in forming the observed patterns of chemical enrichment in the planetary nebulae.

scholarly journals Characterizing global expansion evolution of the ionized matter in planetary nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 352-353
Author(s):  
J. A. López ◽  
M. G. Richer ◽  
M. Pereyra ◽  
M. T. García-Díaz
Keyword(s):  
Galactic Halo ◽  
Evolutionary Rate ◽  
Planetary Nebulae ◽  
Central Star ◽  
Global Expansion ◽  
Kinematic Evolution ◽  
Wide Range ◽  
Model Predictions ◽  
First Time ◽  
Highly Evolved

AbstractBulk outflow or global expansion velocities are presented for a large number of planetary nebulae (PNe) that span a wide range of evolutionary stages and different stellar populations. The sample comprises 133 PNe from the Galactic bulge, 100 mature and highly evolved PNe from the disk, 11 PNe from the Galactic halo and 15 PNe with very low central star masses and low metallicities, for a total of 259 PNe. These results reveal from a statistical perspective the kinematic evolution of the expansion velocities of PNe in relation to changing characteristics of the central star’s wind and ionizing luminosity and as a function of the evolutionary rate determined by the central (CS) mass. The large number of PNe utilized in this work for each group of PNe under study and the homogeneity of the data provide for the first time a solid benchmark form observations for model predictions, as has been described by López et al. (2016).

ISOLATION AND IDENTIFICATION OF RHIZOSPHERIC BACTERIA ASSOCIATED WITH LEMONGRASS FOR POTENTIAL BIOREMEDIATION

2015 ◽  
Vol 77 (24) ◽  
Author(s):  
Najwa Husna Sanusi ◽  
Phang Ing Chia ◽  
Noor Faizul Hadry Nordin
Keyword(s):  
Future Research ◽  
Rrna Gene ◽  
Public Attention ◽  
Isolation And Identification ◽  
Severe Problem ◽  
Rhizospheric Bacteria ◽  
Large Numbers ◽  
Degrading Bacteria ◽  
Cleaner Technology ◽  
Remediation Process

Contamination of soil and groundwater pollution is a severe problem, has been attracting considerable public attention over the last decades. With the demand for green and cleaner technology for remediation process, there is an increased interest in moving away from conventional technologies towards bioremediation technologies. Rhizospheric zone is a suitable place for harboring bacteria that are capable to utilize chemical compounds which will be used either to facilitate growth of bacteria or the host plants. Identification of the specific microbial members should allow for better strategies to enhance biodegradation. This study aimed to isolate and identify the rhizospheric associated microbes of lemongrass (Cymbopogon citratus), a plant that commonly available in South East Asia, which could be used in future research on degradation studies of dibenzofuran. This probably is due to their ability to harbor large numbers of bacteria on their highly branched root systems. A total of 68 strains of dibenzofuran (DF)- degrading bacteria isolated from the rhizospheric soil of lemon grass from 2 different unpolluted sites were characterized. The isolates showed the ability to utilize dibenzofuran as the sole carbon and energy source up to 40 ppm. Identification of the isolates based on 16S rRNA gene sequence assigned them as members of the phyla Proteobacteria and Firmicutes, among which those of the genera, Proteobacteria were most abundant. The presented results indicated the potential of these bacterial isolates in bioremediation of dibenzofuran-contaminated soil.

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