Too Little, Too Late: Evolution in German Counter-Insurgency Methods in Yugoslavia, 1943–1944

2021 ◽  
Vol 34 (3) ◽  
pp. 403-425
Author(s):  
Gaj Trifković
Keyword(s):  
Late Evolution

scholarly journals The Galactic WC and WO stars

2019 ◽  
Vol 621 ◽  
pp. A92 ◽  
Author(s):  
A. A. C. Sander ◽  
W.-R. Hamann ◽  
H. Todt ◽  
R. Hainich ◽  
T. Shenar ◽  
...  
Keyword(s):  
Mass Loss ◽  
Gamma Ray ◽  
Absolute Magnitude ◽  
Mass Range ◽  
Massive Black Holes ◽  
Open Questions ◽  
Late Evolution ◽  
First Time ◽  
Radius Problem

Wolf-Rayet stars of the carbon sequence (WC stars) are an important cornerstone in the late evolution of massive stars before their core collapse. As core-helium burning, hydrogen-free objects with huge mass-loss, they are likely the last observable stage before collapse and thus promising progenitor candidates for type Ib/c supernovae. Their strong mass-loss furthermore provides challenges and constraints to the theory of radiatively driven winds. Thus, the determination of the WC star parameters is of major importance for several astrophysical fields. With Gaia DR2, for the first time parallaxes for a large sample of Galactic WC stars are available, removing major uncertainties inherent to earlier studies. In this work, we re-examine a previously studied sample of WC stars to derive key properties of the Galactic WC population. All quantities depending on the distance are updated, while the underlying spectral analyzes remain untouched. Contrasting earlier assumptions, our study yields that WC stars of the same subtype can significantly vary in absolute magnitude. With Gaia DR2, the picture of the Galactic WC population becomes more complex: We obtain luminosities ranging from logL/L⊙ = 4.9–6.0 with one outlier (WR 119) having logL/L⊙ = 4.7. This indicates that the WC stars are likely formed from a broader initial mass range than previously assumed. We obtain mass-loss rates ranging between log Ṁ = −5.1 and −4.1, with Ṁ ∝ L0.68 and a linear scaling of the modified wind momentum with luminosity. We discuss the implications for stellar evolution, including unsolved issues regarding the need of envelope inflation to address the WR radius problem, and the open questions in regard to the connection of WR stars with Gamma-ray bursts. WC and WO stars are progenitors of massive black holes, collapsing either silently or in a supernova that most-likely has to be preceded by a WO stage.

Mafic and ultrapotassic rocks from the Canyon domain (central Grenville Province): geochemistry and tectonic implications

2012 ◽  
Vol 49 (2) ◽  
pp. 412-433 ◽  
Author(s):  
Carolina Valverde Cardenas ◽  
Aphrodite Indares ◽  
George Jenner
Keyword(s):  
Tectonic Setting ◽  
Source Region ◽  
Crustal Contamination ◽  
Granulite Facies ◽  
Grenville Province ◽  
Mafic Rocks ◽  
Isotopic Signatures ◽  
Late Evolution ◽  
Grenvillian Orogeny ◽  
Laurentian Margin

The Canyon domain and the Banded complex in the Manicouagan area of the Grenville Province preserve a record of magmatic activity from ∼1.4 to 1 Ga. This study focuses on 1.4–1.2 Ga mafic rocks and 1 Ga ultrapotassic dykes. Geochemistry and Sm–Nd isotopic signatures were used to constrain the origin of these rocks and evaluate the changing role of the mantle with time and tectonic setting from the late evolution of the Laurentian margin to the Grenvillian orogeny, in the Manicouagan area. The mafic rocks include layers inferred to represent flows, homogeneous bodies in mafic migmatite, and deformed dykes, all of which were recrystallized under granulite-facies conditions during the Grenvillian orogeny. In spite of the complexities inherent in these deformed and metamorphosed mafic rocks, we were able to recognize suites with distinctive geochemical and isotopic signatures. Integration of this data along with available ages is consistent with a 1.4 Ga continental arc cut by 1.2 Ga non-arc basalts derived from depleted asthenospheric mantle, with varied degrees of crustal contamination and inferred to represent magmatism in an extensional environment. The 1 Ga ultrapotassic dykes postdate the Grenvillian metamorphism. They are extremely enriched in incompatible elements, have negative Nb anomalies, relatively unradiogenic Sr-isotopic compositions (initial 87Sr/86Sr ~ 0.7040) and εNd –3 to –15. Some dykes have compositional characteristics consistent with derivation from the mantle, ruling out crustal contamination as a major process in their petrogenesis. The most likely source region for the ultrapotassic dykes is a metasomatized subcontinental lithospheric mantle, with thermal input from the asthenosphere in association with post-orogenic delamination.

scholarly journals Influence of Carotid Injury in Post-Myocardial Revascularization Surgery and Its Late Evolution

2013 ◽  
Author(s):  
Maria Sol Calero Revelo ◽  
Daniel Pio de Oliveira ◽  
Flávia Bittar Britto Arantes ◽  
Camila Camarço Batista ◽  
João Italo Dias França ◽  
...  
Keyword(s):  
Myocardial Revascularization ◽  
Carotid Injury ◽  
Late Evolution ◽  
Revascularization Surgery

scholarly journals Optically Derived Carbon Abundances in Planetary Nebulae

1983 ◽  
Vol 103 ◽  
pp. 524-524
Author(s):  
H. B. French
Keyword(s):  
Gas Phase ◽  
Planetary Nebulae ◽  
Carbon Star ◽  
Carbon Abundance ◽  
Average Abundance ◽  
Late Evolution ◽  
Solar Abundances ◽  
Low Mass ◽  
The Mean ◽  
Photoelectric Measurements

Gas phase carbon abundances have been determined for a number of bright planetary nebulae from new photoelectric measurements of optical recombination lines (C II λ 4267, C III λ 4650 and C IV λ 4659). Because of blending problems for the latter two features, the abundance for any object may have substantial errors, but the average abundance should be reliable. For the twelve best observed planetaries, this average is C/H = (8.4 ± 2.9 s.d.) x 10−4 by number. If it is assumed that the planetary progenitors had essentially solar abundances, then, based on Cameron's most recent results (C/H = 4.2 × 10−4, O/H = 6.9 × 10−4), it appears that the planetary ejecta have been enriched in carbon, presumably because of dredging of newly synthesized triple α carbon by helium shell flashes during the late evolution of the progenitor. The helium abundance is also slightly high, as would be expected in this interpretation. Since the mean planetary carbon abundance exceeds the solar oxygen abundance, it is possible that the progenitor became a carbon star prior to the ejection of the planetary; that may even have caused the ejection. Because the planetaries in this study were drawn from Peimbert's samples with relatively low mass progenitors (1 – 2.5 M⊙; these are not significantly helium- and nitrogen-rich objects), such a process might be a general feature of late double shell source evolution.

scholarly journals Types of Stellar Instabilities

1980 ◽  
Vol 5 ◽  
pp. 433-436
Author(s):  
P. Ledoux
Keyword(s):  
Neutron Stars ◽  
Linear Theory ◽  
White Dwarfs ◽  
Relativistic Effects ◽  
Significant Information ◽  
Average Value ◽  
Eigen Values ◽  
Late Evolution ◽  
General Relativistic ◽  
Formation Phase

Aside from violent phenomena, regular forms of motions originate often in instabilities and the linear theory with terms ∞ exp (st) yields already significant information. The system, here a spherical star, will be the seat of an instability if R (s) > 0. In general, s will be complex as both conservative (adiabatic) and non-conservative (non-adiabatic) factors are present. However if the latter (small) are neglected, the eigen-values s2 often denoted -σ2 are real. If at least one σ2 < 0, then the star is dynamically unstable.Radial perturbations. If an appropriate average value Γ1 > 4/3, then all σ2 are positive. If Γ < 4/3 (formation phase: ionization; late evolution: nuclear equilibrium; degeneracy in white dwarfs and neutron stars or radiation in very large masses plus general relativistic effects) the fundamental eigenvalue of only becomes negative.

Late Evolution of Close Binaries

1971 ◽  
Vol 168 ◽  
pp. 217 ◽  
Author(s):  
Samuel C. Vila
Keyword(s):  
Close Binaries ◽  
Late Evolution

scholarly journals High-resolution observations of IRAS 08544−4431

2018 ◽  
Vol 614 ◽  
pp. A58 ◽  
Author(s):  
V. Bujarrabal ◽  
A. Castro-Carrizo ◽  
H. Van Winckel ◽  
J. Alcolea ◽  
C. Sánchez Contreras ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Binary System ◽  
Binary Stars ◽  
Asymptotic Giant Branch ◽  
Rotating Disks ◽  
Low Velocity ◽  
Central Mass ◽  
Stellar Orbits ◽  
Disk Rotation ◽  
Late Evolution

Context. Aims. In order to study the effects of rotating disks in the post-asymptotic giant branch (post-AGB) evolution, we observe a class of binary post-AGB stars that seem to be systematically surrounded by equatorial disks and slow outflows. Although the rotating dynamics had only been well identified in three cases, the study of such structures is thought to be fundamental to the understanding of the formation of disks in various phases of the late evolution of binary stars and the ejection of planetary nebulae from evolved stars. Methods. We present ALMA maps of 12CO and 13CO J = 3−2 lines in the source IRAS 08544−4431, which belongs to the above mentioned class of objects. We analyzed the data by means of nebula models, which account for the expectedly composite source and can reproduce the data. From our modeling, we estimated the main nebula parameters, including the structure and dynamics and the density and temperature distributions. We discuss the uncertainties of the derived values and, in particular, their dependence on the distance. Results. Our observations reveal the presence of an equatorial disk in rotation; a low-velocity outflow is also found, probably formed of gas expelled from the disk. The main characteristics of our observations and modeling of IRAS 08544−4431 are similar to those of better studied objects, confirming our interpretation. The disk rotation indicates a total central mass of about 1.8 M⊙, for a distance of 1100 pc. The disk is found to be relatively extended and has a typical diameter of ~4 × 1016 cm. The total nebular mass is ~2 × 10−2 M⊙, of which ~90% corresponds to the disk. Assuming that the outflow is due to mass loss from the disk, we derive a disk lifetime of ~10 000 yr. The disk angular momentum is found to be comparable to that of the binary system at present. Assuming that the disk angular momentum was transferred from the binary system, as expected, the high values of the disk angular momentum in this and other similar disks suggest that the size of the stellar orbits has significantly decreased as a consequence of disk formation.

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