Water in the Atmospheres of Planets.

Bottema, Murk J.; Plummer, William T.; Strong, John

doi:10.1086/109386

Cited by 10 publications

(21 citation statements)

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“…In this approach, stellar and gaseous "fluids" differ by the values of their polytropic indices γ s,g . We choose the value γ s = 2 for the stellar disk which reproduces the empirical "square root" proportionality between the velocity dispersion and the surface density found in galactic disks (Bottema 1992). Additional arguments justifying the description of the collisionless stellar disks by a fluid dynamical approach are given by Kikuchi et al (1997).…”

Section: Basic Equationsmentioning

confidence: 99%

“…The disk of NGC 1566 is observationally well studied. Its rotation curve taken from Bottema (1992) can be approximated by…”

Section: Equilibrium Modelmentioning

confidence: 99%

“…Our choice can be justified as follows. According to Bottema (1992), the measured velocity dispersion in the disk of NGC 1566 gives the real dispersion perpendicular to the galactic disk. In our one-component model, we fix the z-component of the velocity dispersion and hence the surface density and the total mass of the disk, and allow for a variation of the radial velocity dispersion.…”

Section: Equilibrium Modelmentioning

confidence: 99%

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Global spiral modes in multi-component disks

Orlova

Корчагин

Theis

2002

A&A

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Abstract. We performed two-dimensional non-linear hydrodynamical simulations of two-component gravitating disks aimed at studying stability properties of these systems. In agreement with previous analytical and numerical simulations, we find that the cold gas component strongly affects the growth rates of the unstable global spiral modes in the disk. Already a five percent admixture of cold gas increases approximately two-fold the growth rate of the most unstable global mode while a twenty percent gas admixture enhances the modal growth rate by a factor of four. The local stability properties of a two-component disk coupled by self-gravity are governed by a stability criterion similar to Toomre's Q-parameter derived for one-component systems. Using numerical simulations, we analyse the applicability of a two-component local stability criterion for the analysis of the stability properties of global modes. The comparison of non-linear simulations with the analytical stability criterion shows that the two-component disks can be globally unstable while being stable to the local perturbations. The minimum value of the local stability criterion provides, however, a rough estimate of the global stability properties of two-component systems. We find that two-component systems with a content of cold gas of ten percent or less are globally stable if the minimum value of the stability parameter exceeds ∼2.5.

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Section: Basic Equationsmentioning

confidence: 99%

“…The disk of NGC 1566 is observationally well studied. Its rotation curve taken from Bottema (1992) can be approximated by…”

Section: Equilibrium Modelmentioning

confidence: 99%

Section: Equilibrium Modelmentioning

confidence: 99%

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Global spiral modes in multi-component disks

Orlova

Корчагин

Theis

2002

A&A

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“…The rigorous solution of the potential has been given by Peng et al (1978) ϕ(r, z) = −πGα Sandage & Tammann (1981); (2) Bottema (1992); (3) van der Kruit & Freeman (1986); (4) Jarrett et al (2003).…”

Section: The Distribution Of the Vertical Velocity Dispersionmentioning

confidence: 99%

“…Although there are photometric results for NGC 1566 (de Vaucouleurs 1973;Bottema 1992) and 5247 (van der Kruit & Freeman 1986), we cannot use these data directly since the photometric decomposition is very important for our purpose. The photometric decomposition can disentangle the contributions to the total luminosity of the bulge and disk, and this will allow the identification of the disk region.…”

Section: Photometric Decompositionmentioning

confidence: 99%

A new method to determine the thickness of non-edge-on disk galaxies

Zhao

Peng

Tao

2006

A&A

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Aims. We present a new method to determine the thickness of non-edge-on disk galaxies. This method allows us to investigate the mass-to-light ratio of the disk. Methods. Our method is based on the comparison of observations and theory of the distribution of the vertical velocity dispersion, which is obtained from the solution of three dimensional Poisson equations and the galactic dynamical equation. Results. As examples, the thickness and mass-to-light ratio of two disk galaxies, NGC 1566 and NGC 5247, which have been extensively studied by spectroscopy, have been calculated. The calculated results are consistent with observations and support the use of this method. However, due to the small sample size available, the results should be confirmed on other samples of galaxies.

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The Stellar Kinematics of Extragalactic Bulges

Falcón-Barroso

2016

Astrophysics and Space Science Library

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Galactic bulges are complex systems. Once thought to be small-scale versions of elliptical galaxies, advances in astronomical instrumentation (spectroscopy in particular) has revealed a wealth of photometric and kinematic substructure in otherwise simple-looking components. This review provides an overview of how our perspective on galactic bulges has changed over the years. While it is mainly focused on aspects related to the dynamical state of their stars, there will be natural connections to other properties (e.g. morphology, stellar populations) discussed in other reviews in this volume.

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Water in the Atmospheres of Planets.

Cited by 10 publications

References 0 publications

Global spiral modes in multi-component disks

Global spiral modes in multi-component disks

A new method to determine the thickness of non-edge-on disk galaxies

The Stellar Kinematics of Extragalactic Bulges

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