scholarly journals 3D hydrodynamical models of point-symmetric planetary nebulae: the special case of H 1-67

2018 ◽  
Vol 482 (1) ◽  
pp. 1163-1175 ◽  
Author(s):  
J S Rechy-García ◽  
M Peña ◽  
P F Velázquez
Keyword(s):  
Planetary Nebulae ◽  
Hydrodynamical Models ◽  
Special Case

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 Observations and 3D hydrodynamical models of planetary nebulae with Wolf–Rayet type central stars

2016 ◽  
Vol 464 (2) ◽  
pp. 2318-2325 ◽  
Author(s):  
J. S. Rechy-García ◽  
P. F. Velázquez ◽  
M. Peña ◽  
A. C. Raga
Keyword(s):  
Planetary Nebulae ◽  
Hydrodynamical Models ◽  
Central Stars

scholarly journals The kinematics of evolved planetary nebulae

2011 ◽  
Vol 7 (S283) ◽  
pp. 472-473
Author(s):  
E. Margarita Pereyra ◽  
Michael G. Richer ◽  
Jose-Alberto López
Keyword(s):  
Emission Line ◽  
Planetary Nebulae ◽  
Kinematic Characteristic ◽  
Hydrodynamical Models ◽  
Spatially Resolved ◽  
San Pedro ◽  
Advanced Stages ◽  
Photo Ionization ◽  
Echelle Spectroscopy ◽  
Late Stages

AbstractWe have selected a group of 85 evolved planetary nebulae to study their kinematic characteristic based on spatially resolved, long-slit echelle spectroscopy. The data have been drawn from the San Pedro Mártir Kinematic Catalogue of PNe. The aim is to characterize in detail the global kinematics of PNe at advanced stages of evolution with the largest sample of homogenous data used to date for this purpose. The results reveal groups that share kinematic and photo-ionization characteristics of the nebular shell at the different late stages under study. The expansion velocities are typically larger than seen in earlier evolutionary stages, with the largest velocities occurring in objects with very weak or absent [N II]λλ6548, 6584 emission line. These results shall serve to be compared to predictions of hydrodynamical models.

scholarly journals 3D Hydrodynamical models of the planetary nebulae M 1-32 and M 3-15

2016 ◽  
Vol 12 (S323) ◽  
pp. 361-362
Author(s):  
Jackeline S. Rechy-García ◽  
Pablo F. Velázquez ◽  
Miriam Peña ◽  
Alejandro C. Raga
Keyword(s):  
High Resolution ◽  
High Velocity ◽  
3D Model ◽  
Planetary Nebulae ◽  
Emission Lines ◽  
Hydrodynamical Models ◽  
Spectroscopic Observations ◽  
Slow Wind

AbstractHigh-resolution, long-slit spectroscopic observations of two planetary nebulae, M1-32 and M3-15 are presented. The observations were obtained with the 2.1-m telescope at the OAN-SPM, and MES spectrograph. M1-32 shows wide wings on the base of its emission lines and M3-15 has two very faint high-velocity knots. To model both PNe we built a 3D model consisting in a jet interacting with an equatorially concentrated slow wind, emulating the presence of a dense torus, by using the hydrodynamical code Yguazú. The synthetic position-velocity (PV) diagrams obtained from our models reproduce well the observed PV diagrams.

Two-Dimensional Hydrodynamical Models of Planetary Nebulae (PNe)

1989 ◽  
pp. 459-459
Author(s):  
I. V. Igumenshchev ◽  
B. M. Shustov ◽  
A. V. Tutukov
Keyword(s):  
Planetary Nebulae ◽  
Two Dimensional ◽  
Hydrodynamical Models

scholarly journals Radiative Transfer Problems in Planetary Nebulae

1983 ◽  
Vol 103 ◽  
pp. 211-218 ◽  
Author(s):  
David G. Hummer
Keyword(s):  
Radiative Transfer ◽  
Planetary Nebulae ◽  
Important Special Case ◽  
Transfer Problems ◽  
Special Case ◽  
Continuum Formation

In view of the enormous importance of the UV observations of planetary nebulae made possible by the IUE, this review will concentrate primarily on the formation of resonance lines in nebulae; an important special case is that of He II Lyα and its role in the Bowen mechanism. Special attention is given to the effects of dust on the line and continuum formation.

Extreme self-sacrifice beyond fusion: Moral expansiveness and the special case of allyship

2018 ◽  
Vol 41 ◽  
Author(s):  
Daniel Crimston ◽  
Matthew J. Hornsey
Keyword(s):  
General Theory ◽  
Biological Markers ◽  
Natural Environment ◽  
Relevant Dimension ◽  
Special Case

AbstractAs a general theory of extreme self-sacrifice, Whitehouse's article misses one relevant dimension: people's willingness to fight and die in support of entities not bound by biological markers or ancestral kinship (allyship). We discuss research on moral expansiveness, which highlights individuals’ capacity to self-sacrifice for targets that lie outside traditional in-group markers, including racial out-groups, animals, and the natural environment.

Determination of the phase structure of polymerblends by electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 492-493
Author(s):  
Dr. G. Kaemof
Keyword(s):  
Screw Extruder ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Single Screw Extruder ◽  
Transmission Electron ◽  
The Matrix ◽  
Twin Screw ◽  
Special Case ◽  
Microscopic Investigations

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.

Test Validation Without Measurement

2016 ◽  
Vol 32 (3) ◽  
pp. 204-214 ◽  
Author(s):  
Emilie Lacot ◽  
Mohammad H. Afzali ◽  
Stéphane Vautier
Keyword(s):  
Test Data ◽  
Test Scores ◽  
Scientific Explanation ◽  
Test Validation ◽  
Clinical Tests ◽  
Ethical Perspective ◽  
Power Of Test ◽  
Memory Accuracy ◽  
Social Uses ◽  
Special Case

Abstract. Test validation based on usual statistical analyses is paradoxical, as, from a falsificationist perspective, they do not test that test data are ordinal measurements, and, from the ethical perspective, they do not justify the use of test scores. This paper (i) proposes some basic definitions, where measurement is a special case of scientific explanation; starting from the examples of memory accuracy and suicidality as scored by two widely used clinical tests/questionnaires. Moreover, it shows (ii) how to elicit the logic of the observable test events underlying the test scores, and (iii) how the measurability of the target theoretical quantities – memory accuracy and suicidality – can and should be tested at the respondent scale as opposed to the scale of aggregates of respondents. (iv) Criterion-related validity is revisited to stress that invoking the explanative power of test data should draw attention on counterexamples instead of statistical summarization. (v) Finally, it is argued that the justification of the use of test scores in specific settings should be part of the test validation task, because, as tests specialists, psychologists are responsible for proposing their tests for social uses.

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