210
210
Jul 20, 2013
07/13
by
C. F. Gallo; James Q. Feng
texts
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Observations reveal that mature spiral galaxies consist of stars, gases and plasma approximately distributed in a thin disk of circular shape, usually with a central bulge. The rotation velocities quickly increase from the galactic center and then achieve a constant velocity from the core to the periphery. The basic dynamic behavior of a mature spiral galaxy, such as the Milky Way, is well described by simple models balancing Newtonian gravitational forces against the centrifugal forces...
Source: http://arxiv.org/abs/0804.3203v1
2
2.0
Jun 30, 2018
06/18
by
James Q. Feng; C. F. Gallo
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Astronomers have been using the measured luminosity to estimate the {\em luminous mass} of stars, based on empirically established mass-to-light ratio which seems to be only applicable to a special class of stars---the main-sequence stars---with still considerable uncertainties. Another basic tool to determine the mass of a system of stars or galaxies comes from the study of their motion, as Newton demonstrated with his law of gravitation, which yields the {\em gravitational mass}. Because the...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1408.5054
205
205
Jul 20, 2013
07/13
by
James Q. Feng; C. F. Gallo
texts
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For mature spiral galaxies, the rotation velocities quickly increase from the galactic center and achieve a constant velocity from the core to the periphery. This dynamic behavior is described by models balancing Newtonian gravitational and centrifugal forces in rotating thin axisymmetric disks. Freeman's disk assumes a mass density decreasing exponentially with radius which correctly produces rotational velocities which increase from the galactic center to a maximum near the outer core, but...
Source: http://arxiv.org/abs/0804.0217v1
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64
Sep 18, 2013
09/13
by
James Q. Feng; C. F. Gallo
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The measured rotation velocity profiles of mature spiral galaxies are successfully described with a gravitational model consisting of a thin axisymmetric disk of finte radius. The disk is assumed uniformly thin but with variable radial mass density. The governing integral equation is based on mechanical balance between Newtonian gravitational and centrifugal forces (due to galaxy rotation) at each and every point in a finite set of concentric rings. The nondimensionalized mathematical system...
Source: http://arxiv.org/abs/0803.0556v1
132
132
Jul 20, 2013
07/13
by
James Q. Feng; C. F. Gallo
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By numerically solving the mass distribution in a rotating disk based on Newton's laws of motion and gravitation, we demonstrate that the observed flat rotation curves for most spiral galaxies correspond to exponentially decreasing mass density from galactic center for the most of the part except within the central core and near periphery edge. Hence, we believe the galaxies described with our model are consistent with that seen through the eyes of Newton. Although Newton's laws and Kepler's...
Source: http://arxiv.org/abs/1007.3778v3
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33
Sep 23, 2013
09/13
by
James Q. Feng; C. F. Gallo
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An accurate computational method is presented to determine the mass distribution in a rotating thin-disk galaxy from given rotation curve by applying Newtonian dynamics for an axisymmetrically rotating thin disk of finite size with or without a central spherical bulge. The governing integral equation for mass distribution, resulting from the balance between the Newtonian gravitational force and centrifugal force due to rotation at every point on the disk, is transformed via a boundary-element...
Source: http://arxiv.org/abs/1212.5317v2
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53
Sep 21, 2013
09/13
by
James Q. Feng; C. F. Gallo
texts
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We present an efficient, robust computational method for modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies. For a disk galaxy with a typical flat rotation curve, our modeling results show that the surface mass density monotonically decreases from the galactic center toward periphery, according to Newtonian dynamics. In a large portion of the galaxy, the surface mass density follows an approximately exponential law of decay with respect to the galactic radial...
Source: http://arxiv.org/abs/1104.3236v4
