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Fridman, A. M.; Khoruzhii, O. V.; Lyakhovich, V. V.; Avedisova, V. S.; Сильченко, О. К.; Засов, А. В.; Rastorguev, A. S.; Afanasiev, V. L.; Додонов, С. Н.; Boulesteix, J.

doi:10.1023/a:1000814215934

Cited by 20 publications

(34 citation statements)

References 3 publications

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“…It seems that the parameter variations obtained by formal use of the tilted-rings model is often a consequence of non-circular motions which are not taken into account by this method. If the variations of either i or PA 0 (or x 0 , y 0 ) bear a systematic character, it may be an indication that the presence of a spiral density wave (or bar) should be taken into account Fridman et al 1997).…”

Section: "Kinematic" Orientation Parameters Of Galactic Disksmentioning

confidence: 99%

“…A consistent and reliable way to estimate different components of the Fourier spectrum of the line-of-sight velocity field (and particularly the rotation velocity) was proposed and validated by Lyakhovich et al (1997), Fridman et al (1997Fridman et al ( , 2001a, Burlak et al (2000). It is based on the application of a least-square method to the expansion of the azimuthal distribution of the observed gas velocities into the truncated Fourier series.…”

Section: "Kinematic" Orientation Parameters Of Galactic Disksmentioning

confidence: 99%

“…Such interference makes it necessary to work out a special method to separate the circular and non-circular motion consistently. This method was proposed and described in detail in the papers by Lyakhovich et al (1997), Fridman et al (1997Fridman et al ( , 2001). These authors also showed that, in general, ignoring the influence of systematic (density-wave related) noncircular motion onto the line-of-sight velocities may prompt systematic errors in estimations of orientation parameters and lead to a wrong conclusion about their radial variations, even in the case of their constancy.…”

Section: Introductionmentioning

confidence: 99%

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The orientation parameters and rotation curves of 15 spiral galaxies

Fridman

Afanasiev

Додонов

et al. 2005

A&A

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Abstract. We analyzed ionized gas motion and disk orientation parameters for 15 spiral galaxies. Their velocity fields were measured with the Hα emission line by using the Fabry-Perot interferometer at the 6 m telescope of SAO RAS. Special attention is paid to the problem of estimating the position angle of the major axis (PA 0 ) and the inclination (i) of a disk, which strongly affect the derived circular rotation velocity. We discuss and compare different methods of obtaining these parameters from kinematic and photometric observations, taking into account the presence of regular velocity (brightness) perturbations caused by spiral density waves. It is shown that the commonly used method of tilted rings may lead to systematic errors in the estimation of orientation parameters (and hence of circular velocity) being applied to galaxies with an ordered spiral structure. Instead we recommend using an assumption of constancy of i and PA 0 along a radius, to estimate these parameters. For each galaxy of our sample we present monochromatic Hα-and continuum maps, velocity fields of ionized gas, and the mean rotation curves in the frame of a model of pure circular gas motion. Significant deviations from circular motion with amplitudes of several tens of km s −1 (or higher) are found in almost all galaxies. The character and possible nature of the non-circular motion are briefly discussed.

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Section: "Kinematic" Orientation Parameters Of Galactic Disksmentioning

confidence: 99%

Section: "Kinematic" Orientation Parameters Of Galactic Disksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The orientation parameters and rotation curves of 15 spiral galaxies

Fridman

Afanasiev

Додонов

et al. 2005

A&A

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“…In the near-infrared, the morphology of older star-dominated disk indicates a simple classification scheme: the dominant Fourier m-mode. Fridman et al (1998) and Burlak et al (2000) detected m = 1−9 spiral modes in relatively young stellar population of the nearly face-on galaxies from observations in the H α line. A ubiquity of low-m (m = 1−4) modes was confirmed.…”

Section: Linear Theorymentioning

confidence: 99%

Quasi-linear theory of the Jeans instability in disk-shaped galaxies

Griv

Gedalin

Yuan

2002

A&A

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Abstract. We analyse the reaction between almost aperiodically growing Jeans-unstable gravity perturbations and stars of a rotating and spatially inhomogeneous disk of flat galaxies. A mathematical formalism in the approximation of weak turbulence (a quasi-linearization of the Boltzmann collisionless kinetic equation) is developed. A diffusion equation in configuration space is derived which describes the change in the main body of equilibrium distribution of stars. The distortion in phase space resulting from such a wave-star interaction is studied. The theory, applied to the Solar neighborhood, accounts for the observed Schwarzschild shape of the velocity ellipsoid, the increase in the random stellar velocities with age, and the essential radial migration of the Sun from its birth-place in the inner part of the Galaxy outwards during its lifetime.

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“…Mrk 1040, Afanasiev and Fridman 1993), and of a gravitational instability, when K 2 > 0, (e.g. NGC 157, NGC 3893, Fridman et al1997bFridman et al , 1999.…”

Section: Velocity Fields In Spiral Galaxiesmentioning

confidence: 99%