نتایج جستجو برای: stellar configurations

تعداد نتایج: 141171  

Journal: :iranian journal of astronomy and astrophysics 2014
hosein haghi hamed ghasemi hongsheng zhao

the rotation curves of a sample of 46 low- and high-surface brightness galaxies are considered in the context of milgrom's modi_ed dynamics (mond) to test a new interpolating function proposed by zhao et al. (2010) [1] and compare with the results of simple interpolating function. the predicted rotation curves are calculated from the total baryonic matter based on the b-band surface photometry,...

2009
Andreas Reisenegger

Context. Long-lived, large-scale magnetic field configurations exist in upper main sequence, white dwarf, and neutron stars. Externally, these fields have a strong dipolar component, while their internal structure and evolution are uncertain but highly relevant to several problems in stellar and high-energy astrophysics. Aims. We discuss the main properties expected for the stable magnetic conf...

Journal: :journal of sciences islamic republic of iran 0

we have studied the effect of hypothetical cosmions on the core stability of main sequence stars (of populations i and ii). cosmions, with a mass of 4-10 gev/c2 and a scattering cross section with nucleons of approximately 10-36 cm2 could prevail in transporting heat in the stellar cores. raby [17] showed the existence of a local thermal instability caused by the presence of cosmions in the sol...

2003
Yu-Qing Lou Yue Zou

We construct aligned and unaligned stationary perturbation configurations in a composite system of stellar and coplanarly magnetized gaseous singular isothermal discs (SIDs) coupled by gravity. This study extends recent analyses on (magnetized) SIDs of Shu et al., Lou and Lou & Shen. By this model, we intend to provide a conceptual framework to gain insights for multi-wavelength large-scale str...

2009
V. Duez S. Mathis

The understanding of fossil fields origin, topology and stability is one of the corner stone of the stellar magnetism theory. On one hand, since they survive over secular time-scales, they may modify the structure and the evolution of their host stars. On the other hand, they must have a complex stable structure since it has been demonstrated by Tayler and collaborators that simplest purely pol...

2009
D. W. Latham Géza Kovács R. W. Noyes G. W. Marcy D. A. Fischer R. P. Butler D. D. Sasselov G. A. Esquerdo A. Shporer T. Mazeh R. P. Stefanik H. Isaacson

We present HATNet observations of XO-5b, confirming its planetary nature based on evidence beyond that described in the announcement of Burke et al. (2008), namely, the lack of significant correlation between spectral bisector variations and orbital phase. In addition, using extensive spectroscopic measurements spanning multiple seasons, we investigate the relatively large scatter in the spectr...

2009
Attay Kovetz Ofer Yaron Dina Prialnik

We present a new stellar evolution code and a set of results, demonstrating its capability at calculating full evolutionary tracks for a wide range of masses and metallicities. The code is fast and efficient, and is capable of following through all evolutionary phases, without interruption or human intervention. It is meant to be used also in the context of modeling the evolution of dense stell...

2002
S Wolf

A revised and greatly improved version of the 3D continuum radiative transfer code MC3D is presented. It is based on the Monte-Carlo method and solves the radiative transfer problem self-consistently. It is designed for the simulation of dust temperatures in arbitrary geometric configurations and the resulting observables: spectral energy distributions, wavelength-dependent images, and polariza...

2009
Laura V. Sales Amina Helmi Giuseppina Battaglia

We use N-body simulations to study the effects of tides on the kinematical structure of satellite galaxies orbiting a Milky Way-like potential. Our work is motivated by observations of dwarf spheroidal galaxies in the Local Group, for which often a distinction is possible between a cold centrally concentrated metal rich and a hot, extended metal poor population. Here we focus on the evolution o...

Journal: :Physics 2021

A Newtonian-like theory inspired by the Brans–Dicke gravitational Lagrangian has been recently proposed us. For static configurations, coupling acquires an intrinsic spatial dependence within matter distribution. Therefore, interior of astrophysical configurations may provide a testable environment for this approach as long no screening mechanism is evoked. In work, we focus on stellar hydrosta...

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