scholarly journals Modeling of Spiral Structure in a Multi-Component Milky Way-Like Galaxy

Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 29
Author(s):  
Sergey Khrapov ◽  
Alexander Khoperskov ◽  
Vladimir Korchagin
Keyword(s):  
Milky Way ◽  
Spiral Structure ◽  
Gravitational Interaction ◽  
Equations Of Motion ◽  
Milky Way Galaxy ◽  
Density Distributions ◽  
Maximum Value ◽  
Central Regions ◽  
Axis Length ◽  
Bar Formation

Using recent observational data, we construct a set of multi-component equilibrium models of the disk of a Milky Way-like galaxy. The disk dynamics are studied using collisionless-gaseous numerical simulations, based on the joined integration of the equations of motion for the collision-less particles using direct integration of gravitational interaction and the gaseous SPH-particles. We find that after approximately one Gyr, a prominent central bar is formed having a semi-axis length of about three kpc, together with a multi-armed spiral pattern represented by a superposition of m= 2-, 3-, and 4-armed spirals. The spiral structure and the bar exist for at least 3 Gyr in our simulations. The existence of the Milky Way bar imposes limitations on the density distributions in the subsystems of the Milky Way galaxy. We find that a bar does not form if the radial scale length of the density distribution in the disk exceeds 2.6 kpc. As expected, the bar formation is also suppressed by a compact massive stellar bulge. We also demonstrate that the maximum value in the rotation curve of the disk of the Milky Way galaxy, as found in its central regions, is explained by non-circular motion due to the presence of a bar and its orientation relative to an observer.

scholarly journals Role of Gaseous Disk in the Formation of the Spiral Structure of the Milky Way Galaxy

2016 ◽  
Vol 25 (4) ◽  
Author(s):  
V. I. Korchagin ◽  
S. A. Khoperskov ◽  
A. V. Khoperskov
Keyword(s):  
Milky Way ◽  
Spiral Structure ◽  
Stellar Disk ◽  
Milky Way Galaxy ◽  
Density Distributions ◽  
Disk Rotation ◽  
Gaseous Component ◽  
Axisymmetric Structure ◽  
Stellar Density

AbstractWe use observational gaseous and stellar density distributions in the disk of the Milky Way (MW) galaxy together with the disk rotation curve and measured disk velocity dispersion to build collisionless and combined collisionless-gaseous equilibrium models of the Milky Way disk. A purely collisionless MW disk is unstable towards the development of a central bar, so that during the nonlinear stage of instability the stellar bar is a dominant non-axisymmetric structure developing the disk. A ten percent admixture of a gaseous component leads to the development of a three-armed spiral structure in the stellar disk, decoupled spatially from the central bar-like structure. In our simulations, the spiral structure lasts for about 3 Gyr.

scholarly journals The spiral structure of our Milky Way Galaxy

2009 ◽  
Vol 499 (2) ◽  
pp. 473-482 ◽  
Author(s):  
L. G. Hou ◽  
J. L. Han ◽  
W. B. Shi
Keyword(s):  
Milky Way ◽  
Spiral Structure ◽  
Milky Way Galaxy

scholarly journals On the spiral structure of the Milky Way Galaxy

2011 ◽  
Vol 55 (2) ◽  
pp. 108-122 ◽  
Author(s):  
Yu. N. Efremov
Keyword(s):  
Milky Way ◽  
Spiral Structure ◽  
Milky Way Galaxy

scholarly journals Spiral structure of the Milky Way and external galaxies

1985 ◽  
Vol 106 ◽  
pp. 255-272 ◽  
Author(s):  
Debra Meloy Elmegreen
Keyword(s):  
Milky Way ◽  
Spiral Structure ◽  
Vantage Point ◽  
Milky Way Galaxy ◽  
External Galaxies ◽  
Insight Into

The spiral structure of the Milky Way galaxy has always been somewhat elusive because of our internal vantage point. This review will present methods and data for determining the overall pattern, and will summarize various models that have been proposed. Observations of spirals in external galaxies will also be discussed, because they can provide insight into the spiral structure of the Milky Way.

scholarly journals An innovative model of a non-relativist universe

2020 ◽  
Vol 217 ◽  
pp. 11002
Author(s):  
Olga Baryshnikova ◽  
Catherine Sapelnik ◽  
Lyudmila Fedoseeva
Keyword(s):  
Hubble Parameter ◽  
Milky Way ◽  
Local Universe ◽  
Milky Way Galaxy ◽  
Conservation Of Energy ◽  
Classical Formulation ◽  
Maximum Value ◽  
Proposed Model ◽  
Age Of The Universe ◽  
The Universe

The paper investigates a model of the local Universe based on the concepts of nonrelativistic physics. The space-time boundaries of its applicability are estimated. The finiteness of the Universe in space and time arising from the analysis of the field of forces and energy fields of the Universe is affirmed. The necessity of the existence of “dark matter” in the proposed model is shown. On the basis of the presented model (using the modern values of the Hubble parameter and the density of the substance of the Universe), the following are estimated: the age of the Universe; the mass of its substance; period of her life cycle; acceleration of the movement of matter, etc. The dependences of the density of matter (and its minimum value), the radius of the Universe (and its maximum value), and the Hubble parameter on time are obtained. The position of the Milky Way galaxy in the Universe has also been estimated. It is shown that the law of conservation of energy in its classical formulation is not applicable to the Universe as a whole. It is argued that after a while the laws of classical physics will be applicable to the entire Universe as a whole.

scholarly journals Tidal Torques Dynamical Friction and the Structure of Clusters of Galaxies

1999 ◽  
Vol 183 ◽  
pp. 245-245
Author(s):  
A. Del Popolo ◽  
M. Gambera
Keyword(s):  
Gravitational Interaction ◽  
Equations Of Motion ◽  
Joint Effect ◽  
Critical Threshold ◽  
Selection Function ◽  
Dynamical Friction ◽  
Density Peaks ◽  
Central Regions ◽  
Bias Level ◽  
Tidal Torques

We study the joint effect of tidal torques and dynamical friction on the collapse of density peaks solving numerically the equations of motion of a shell of barionic matter falling into the central regions of a cluster of galaxies. We calculate the evolution of the expansion parameter, a(t), of the perturbation using a coefficient of dynamical friction ηcl obtained from a clustered system and taking into account the gravitational interaction of the quadrupole moment of the system with the tidal field of the matter of the neighboring proto-galaxies. We find that the tidal torques and the dynamical friction slow down the collapse of low-v (v < 3) peaks producing an observable variation of a(t) (Del Popolo & Gambera 1996,1997). As consequence we have a reduction of the mass bound to collapsed perturbations and a raising of the critical threshold, δc. Besides, we have a bias of dynamical nature arises because high-density peaks preferentially collapse to form halos within which visible objects. We calculate the selection function and using it and the prescriptions given by Bardeen et al. 1986 we find a value of the coefficient of bias, b = 2.25 on clusters scales for Rf = 4h–1Mpc comparable both with that obtained from the mean mass-to-light ratio of clusters, APM survey, or from N-body simulations combined with hydrodynamical models and with the values of b given by Kauffmann et al. 1996. This means that non-radial motions and dynamical friction play a significant role in determining the bias level.

The Long View of Planetary Systems

2018 ◽  
Author(s):  
Karel Schrijver
Keyword(s):  
Solar System ◽  
Milky Way ◽  
Planetary Systems ◽  
Giant Planets ◽  
Milky Way Galaxy ◽  
Population Statistics ◽  
The Past ◽  
General Terms ◽  
The Galaxy ◽  
The Universe

How many planetary systems formed before our’s did, and how many will form after? How old is the average exoplanet in the Galaxy? When did the earliest planets start forming? How different are the ages of terrestrial and giant planets? And, ultimately, what will the fate be of our Solar System, of the Milky Way Galaxy, and of the Universe around us? We cannot know the fate of individual exoplanets with great certainty, but based on population statistics this chapter sketches the past, present, and future of exoworlds and of our Earth in general terms.

scholarly journals A Statistical Estimation of the Occurrence of Extraterrestrial Intelligence in the Milky Way Galaxy

Galaxies ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 5
Author(s):  
Xiang Cai ◽  
Jonathan H. Jiang ◽  
Kristen A. Fahy ◽  
Yuk L. Yung
Keyword(s):  
Statistical Estimation ◽  
Milky Way ◽  
Galactic Center ◽  
Model Simulation ◽  
Temporal Variations ◽  
Extraterrestrial Intelligence ◽  
Milky Way Galaxy ◽  
The Galaxy ◽  
Peak Location ◽  
Intelligent Life

In the field of astrobiology, the precise location, prevalence, and age of potential extraterrestrial intelligence (ETI) have not been explicitly explored. Here, we address these inquiries using an empirical galactic simulation model to analyze the spatial–temporal variations and the prevalence of potential ETI within the Galaxy. This model estimates the occurrence of ETI, providing guidance on where to look for intelligent life in the Search for ETI (SETI) with a set of criteria, including well-established astrophysical properties of the Milky Way. Further, typically overlooked factors such as the process of abiogenesis, different evolutionary timescales, and potential self-annihilation are incorporated to explore the growth propensity of ETI. We examine three major parameters: (1) the likelihood rate of abiogenesis (λA); (2) evolutionary timescales (Tevo); and (3) probability of self-annihilation of complex life (Pann). We found Pann to be the most influential parameter determining the quantity and age of galactic intelligent life. Our model simulation also identified a peak location for ETI at an annular region approximately 4 kpc from the galactic center around 8 billion years (Gyrs), with complex life decreasing temporally and spatially from the peak point, asserting a high likelihood of intelligent life in the galactic inner disk. The simulated age distributions also suggest that most of the intelligent life in our galaxy are young, thus making observation or detection difficult.

scholarly journals On the maintenance of spiral structure

1979 ◽  
Vol 84 ◽  
pp. 151-153
Author(s):  
James W-K. Mark ◽  
Linda Sugiyama ◽  
Robert H. Berman ◽  
Giuseppe Bertin
Keyword(s):  
Spiral Structure ◽  
Travelling Waves ◽  
Integral Condition ◽  
Stimulated Emission ◽  
Stellar Disk ◽  
Wave System ◽  
Wave Amplification ◽  
Corotation Radius ◽  
The Galaxy ◽  
Central Regions

A concentrated nuclear bulge with about 30% of the galaxy mass is sufficient (Lin, 1975; Berman and Mark, 1978) to eliminate strong bar-forming instabilities which dominate the dynamics of the stellar disk. Weak bar-like or oval distortions might remain depending on the model. In such systems self-excited discrete modes give rise to global spiral patterns which are maintained in the presence of differential rotation and dissipation (cf. especially the spiral patterns in Bertin et al., 1977, 1978). These spiral modes are standing waves that are physically analyzable (Mark, 1977) into a superposition of two travelling waves propagating in opposite directions back and forth between galactic central regions and corotation (a resonator). Only a few discrete pattern frequencies are allowed. An interpretation is that the central regions and corotation radius must be sufficiently far apart so that a Bohr-Sommerfeld type of phase-integral condition is satisfied for the wave system of each mode. The temporal growth of these modes is mostly due to an effect of Wave Amplification by Stimulated Emission (of Rotating Spirals, abbrev. WASERS, cf. Mark 1976) which occurs in the vicinity of corotation. In some galaxies one mode might be predominent while other galaxies could exhibit more complicated spiral structure because several modes are present. Weak barlike or oval distortions hardly interfere with the structure of these modes. But they might nevertheless contribute partially towards strengthening the growth of one mode relative to another, as well as affecting the kinematics of the gaseous component.

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