Viscoelastic pulsational mode

Dutta, Pooja; Karmakar, Pralay Kumar

doi:10.1007/s10509-017-3120-1

Cited by 20 publications

(15 citation statements)

References 17 publications

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“…Thus, we can infer that both ne0 and ni0 act as destabilizing agencies to the pulsating cloud responsible for active star formation processes via the canonical gravitational collapse mechanism. If this result is compared with the closely correlated findings available in the literature [22], it is found that ne0 and ni0 conjugationally act as destabilizers and stabilizers for a viscoelastic cloud fluid. It enables us to conclude that ne0 acting as a destabilizing agency to the self-gravitating DMC is a common feature realistically experience in both the kinetic and fluid frameworks.…”

Section: Resultssupporting

confidence: 59%

“…The various lines link to md = 2×10 -8 g (red, solid line), md = 3×10 -8 g (blue, dashed line), and md = 4×10 -8 g (black, dotted line), respectively. The different parametric input values for the numerical analysis adopted from reliable astronomical literature [5,6,[16][17][18][19][20][21][22][23] used here are me = 9.1×10 -28 g, mi = 1.67×10 -24 g, ne0 = 1×10 6 cm -3 , ni0 = 5×10 6 cm -3 , ndn0 = 4 cm -3 , ndc0 = 2 cm -3 , Te≃Ti≃1 eV, Td ≃ 2×10 -2 eV, and Zd= 100. It is interestingly seen that the real frequency part (Figs.…”

Section: Resultsmentioning

confidence: 99%

“…The frictional coupling of the gravitational attraction (inwards) and electrostatic repulsion (outwards) of the massive charged grains constituting the DMCs gives rise to a new mode of the Jeans condensation, termed as the pulsational mode of gravitational collapse (PMGC), which is a purely hybrid mode composed of the gravitoelectrostatic degrees of freedom [5,6]. The PMGC dynamics has been extensively studied in the framework of multicomponent fluid model formalisms only in different astronomical circumstances [5,6,[20][21][22][23][24][25]. In the recent past, the hybrid instability dynamics excitable in a strongly coupled magnetized self-gravitating conducting dusty plasma system has been investigated [15].…”

Section: Introductionmentioning

confidence: 99%

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A kinetic theory of the pulsational mode of gravitational collapse in star-forming molecular clouds

Challam

Karmakar

2021

Preprint

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A kinetic theory formulation of the pulsational mode of gravitational collapse (PMGC) in a complex unmagnetized self-gravitating partially ionized dense molecular cloud (DMC) is proposed. Applying a linear normal mode analysis, a quintic linear dispersion relation with a unique set of multi-parametric plasma-dependent coefficients is obtained. The reliability of the calculation scheme is validated in light of the various predictions available in the literature. It is then numerically analyzed in the parametric windows of judicious realistic input values. Our results indicate that the dust mass, equilibrium electron density, and equilibrium ion density act as destabilizing agencies to the PMGC evolution. In contrast, the dust charge number, equilibrium dust density, and dust temperature act as stabilizing agencies. The oscillatory and propagatory features of the PMGC are illustratively explained and comparatively validated in accordance with the observed astrophysical scenarios. This paper ends up with a brief highlight of the non-trivial implications and applications of the results actualizable in the self-gravitational collapse mechanism leading to varied structure formation processes in the mysterious astrocosmic universe.

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Section: Resultssupporting

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A kinetic theory of the pulsational mode of gravitational collapse in star-forming molecular clouds

Challam

Karmakar

2021

Preprint

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“…For the β 0 = 0.2 case, the rotation speed varies between 0.3 and 0.9 times the Keplerian velocity, indicating that this cloud has gone through an efficient phase of angular momentum redistribution (Dutta 2015b). However, for β 0 > 0.05 the collapsing cloud is almost completely rotationally supported throughout and the gas at higher densities is relatively cold.…”

Section: Velocity Structurementioning

confidence: 97%

On the effects of rotation in primordial star-forming clouds

Dutta

2015

A&A

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Context. The thermodynamical evolution of gas during the collapse of the primordial star-forming cloud depends significantly on the initial degree of rotation. Aims. However, there is no clear understanding of how the initial rotation can affect the heating and cooling process and hence the temperature that leads to the fragmentation of the gas during Population III star formation. Methods. We report the results from three-dimensional, smoothed-particle hydrodynamics (SPH) simulations of a rotating selfgravitating primordial gas cloud with a modified version of the Gadget-2 code, in which the initial ratio of the rotational to the gravitational energy (β 0 ) is varied over two orders of magnitude. Results. We find that despite the lack of any initial turbulence and magnetic fields in the clouds, the angular momentum distribution leads to the formation and build-up of a disk that fragments into several clumps. We further examine the behavior of the protostars that form in both idealized as well as more realistic minihalos from the cosmological simulations. The thermodynamical evolution and the fragmentation behavior of the cosmological minihalos are similar to that of the artificial cases, especially in those with a similar β 0 -parameter. Protostars with a higher rotation support exhibit spiral-arm-like structures on several scales, and have lower accretion rates. These type of clouds tend to fragment more, while some of the protostars escape from the cluster with the possibility of surviving until the present day. They also take much longer to form compared to their slowly rotating counterparts. Conclusions. We conclude that the use of appropriate initial conditions of the gas in minihalos is a pivotal and decisive quantity to study the evolution and final fate of the primordial stars.

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“…Sürece ilişkin gerek gönüllü anne-babanın gerekse taşıyıcı annenin yazılı rızasının alınacağı öngörülmüştür. Bunun dışında, taşıyıcı annelik sürecinin öncesinde veya sonrasında evlat edinme sürecinin işletilmesine veya konuya ilişkin mahkeme yahut kurum kararının alınmasına hukuken gerek olmadığı belirtilmiştir 125 . Başka ülkelerin vatandaşı olan gönüllü anne-babaların da -Rus vatandaşı olan diğer çiftler gibi-bu süreçle doğan çocukları için kendilerini hukuken anne-baba olarak gösteren Rusya doğum kayıtlarını edineceği belirtilmiştir 126 .…”

Section: Amerika Birleşik Devletleriunclassified

Aile Hukukunda Zor Bir Dönemeç: Karşılaştırmalı Hukuk Bakış Açısıyla Taşıyıcı Anneliğe İlişkin Güncel Gelişmeler

Börü¹

2019

PPIL

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Öz Taşıyıcı annelik gerek devletlerin iç hukuklarında gerekse uluslararası hukuk çerçevesinde aile hukukunun en ilginç ve karmaşık konularından biri haline gelmiştir. Roma hukukundan günümüze gelen 'mater semper certa est' ('Anne her zaman bellidir') prensibinin genelgeçer kesinliği modern üreme tekniklerinin ilerlemesiyle birlikte sarsılmaya başlamıştır. Devletler arasındaki yasal düzenleme ve uygulama farklılıkları taşıyıcı annelik turizminin doğmasına sebep olmuştur. Avrupa ülkelerinde taşıyıcı anneliğe ilişkin katı tutumun özellikle AİHM'in Mennesson ve Labassee davalarında vermiş olduğu kararların ardından yumuşamaya başladığı görülmektedir. Türk hukukunda ise konunun kısmen ele alındığı ve uygulamanın yasak kabul edildiği görülmektedir. Çalışmamızda konuyu farklı yönleriyle, karşılaştırmalı hukuk düzenlemeleri ve AİHM kararları çerçevesinde ayrıntılı şekilde ele almaya çalıştık. Böylece dünyada konuya ilişkin güncel gelişmeler ışığında, Türk hukukunda konuya ilişkin bakış açısına ve yapılacak değerlendirmelere katkı sağlamayı diliyoruz. Anahtar Kelimeler Taşıyıcı annelik • Taşıyıcı annelik sözleşmesi • Üremeye yardımcı tedavi uygulamaları ve üremeye yardımcı tedavi merkezleri hakkında yönetmelik (ÜYTE) • Soybağı • AİHM'in 'Mennesson' ve 'Labassee' kararları

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Viscoelastic pulsational mode

Cited by 20 publications

References 17 publications

A kinetic theory of the pulsational mode of gravitational collapse in star-forming molecular clouds

A kinetic theory of the pulsational mode of gravitational collapse in star-forming molecular clouds

On the effects of rotation in primordial star-forming clouds

Aile Hukukunda Zor Bir Dönemeç: Karşılaştırmalı Hukuk Bakış Açısıyla Taşıyıcı Anneliğe İlişkin Güncel Gelişmeler

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