scholarly journals N-body simulations of interactions and mergings in small galaxy groups

2000 ◽  
Vol 174 ◽  
pp. 245-254 ◽  
Author(s):  
E. Athanassoula
Keyword(s):  
Initial Conditions ◽  
Dynamical Evolution ◽  
Elliptical Galaxies ◽  
Compact Groups ◽  
Disc Galaxy ◽  
Galaxy Groups ◽  
Advantages And Disadvantages ◽  
Group I ◽  
Ongoing Formation ◽  
Disc Galaxies

AbstractIn this paper I focus on three topics related to the dynamical evolution of small galaxy groups, for which the input of N-body simulations has been decisive. These are the merging rates in compact groups, the properties of remnants of multiple mergers, and the evolution of disc galaxies surrounded by one or more satellites. The short dynamical times of compact groups make it difficult to understand why such groups are observed at all. N-body simulations have pointed out two possible classes of solutions to this problem. The first one proposes that there is ongoing formation of compact groups, or that the longevity of the group is due to secondary infall. For the second class of solutions the longevity of compact groups is due either to their specific initial conditions, or to a massive common halo, encompassing the whole group. I discuss here these alternatives, together with their respective advantages and disadvantages. I then turn to the structure of remnants of multiple mergers and compare the results of N-body simulations with the properties of observed elliptical galaxies. Finally I discuss the dynamical evolution of a disc galaxy surrounded by one or more spherical satellites.

scholarly journals Tracing interactions in HCGs through the H I

2000 ◽  
Vol 174 ◽  
pp. 167-173 ◽  
Author(s):  
L. Verdes-Montenegro ◽  
M. S. Yun ◽  
B. A. Williams ◽  
W. K. Huchtmeier ◽  
A. Del Olmo ◽  
...  
Keyword(s):  
Velocity Dispersion ◽  
Group Velocity Dispersion ◽  
Dynamical Evolution ◽  
Compact Groups ◽  
High Group ◽  
X Ray ◽  
Hot Gas ◽  
Isolated Galaxies ◽  
Global Study ◽  
Hickson Compact Groups

AbstractWe present a global study of Hɪ spectral line mapping for 16 Hickson Compact Groups (HCGs) combining new and unpublished VLA data, plus the analysis of the Hɪ content of individual galaxies. Sixty percent of the groups show morphological and kinematical signs of perturbations (from multiple tidal features to concentration of the Hɪ in a single enveloping cloud) and sixty five of the resolved galaxies are found to be Hɪ deficient with respect to a sample of isolated galaxies. In total, 77% of the groups suffer interactions among all its members which provides strong evidence of their reality. We find that dynamical evolution does not always produce Hɪ deficiency, but when this deficiency is observed, it appears to correlate with a high group velocity dispersion and in some cases with the presence of a first-ranked elliptical. The X-ray data available for our sample are not sensitive enough for a comparison with the Hɪ mass; however this study does suggest a correlation between Hɪ deficiency and hot gas since velocity dispersions are known from the literature to correlate with X-ray luminosity.

scholarly journals Mass determination of the 1:3:5 near-resonant planets transiting GJ 9827 (K2-135)

2018 ◽  
Vol 618 ◽  
pp. A116 ◽  
Author(s):  
J. Prieto-Arranz ◽  
E. Palle ◽  
D. Gandolfi ◽  
O. Barragán ◽  
E. W. Guenther ◽  
...  
Keyword(s):  
Planetary System ◽  
Initial Conditions ◽  
Dynamical Evolution ◽  
Space Mission ◽  
Mass Determination ◽  
Velocity Measurements ◽  
Orbital Periods ◽  
The Masses ◽  
Better Than

Context. Multiplanet systems are excellent laboratories to test planet formation models as all planets are formed under the same initial conditions. In this context, systems transiting bright stars can play a key role, since planetary masses, radii, and bulk densities can be measured. Aims. GJ 9827 (K2-135) has recently been found to host a tightly packed system consisting of three transiting small planets whose orbital periods of 1.2, 3.6, and 6.2 days are near the 1:3:5 ratio. GJ 9827 hosts the nearest planetary system (~30 pc) detected by NASA’s Kepler or K2 space mission. Its brightness (V = 10.35 mag) makes the star an ideal target for detailed studies of the properties of its planets. Methods. Combining the K2 photometry with high-precision radial-velocity measurements gathered with the FIES, HARPS, and HARPS-N spectrographs we revised the system parameters and derive the masses of the three planets. Results. We find that GJ 9827 b has a mass of Mb = 3.69−0.46+0.48 M⊕ and a radius of Rb = 1.58−0.13+0.14 R⊕, yielding a mean density of ρb = 5.11−1.27+1.74 g cm−3. GJ 9827 c has a mass of Mc = 1.45−0.57+0.58 M⊕, radius of Rc = 1.24−0.11+0.11 R⊕, and a mean density of ρc = 4.13−1.77+2.31 g cm−3. For GJ 9827 d, we derive Md = 1.45−0.57+0.58 M⊕, Rd = 1.24−0.11+0.11 R⊕, and ρd = 1.51−0.53+0.71 g cm−3. Conclusions. GJ 9827 is one of the few known transiting planetary systems for which the masses of all planets have been determined with a precision better than 30%. This system is particularly interesting because all three planets are close to the limit between super-Earths and sub-Neptunes. The planetary bulk compositions are compatible with a scenario where all three planets formed with similar core and atmosphere compositions, and we speculate that while GJ 9827 b and GJ 9827 c lost their atmospheric envelopes, GJ 9827 d maintained its primordial atmosphere, owing to the much lower stellarirradiation. This makes GJ 9827 one of the very few systems where the dynamical evolution and the atmosphericescape can be studied in detail for all planets, helping us to understand how compact systems form and evolve.

scholarly journals MERGERS IN GALAXY GROUPS. II. THE FUNDAMENTAL PLANE OF ELLIPTICAL GALAXIES

2015 ◽  
Vol 803 (2) ◽  
pp. 78 ◽  
Author(s):  
Dan Taranu ◽  
John Dubinski ◽  
H. K. C. Yee
Keyword(s):  
Elliptical Galaxies ◽  
Fundamental Plane ◽  
Galaxy Groups

scholarly journals Evaluation of Delorme’s Procedure in the Treatment of Complete Rectal Prolapse- A Comparison with Abdominal Rectopexy (Well’s procedure)

2021 ◽  
Vol 34 (1) ◽  
pp. 40-46
Author(s):  
Md Ariful Alam Suman ◽  
Md Habibullah Sarkar ◽  
Istiak Ahmed ◽  
Sulatanul Abedin ◽  
Md Shohidul Islam ◽  
...  
Keyword(s):  
Rectal Prolapse ◽  
Hospital Stay ◽  
P Value ◽  
Complete Rectal Prolapse ◽  
Advantages And Disadvantages ◽  
Group I ◽  
Abdominal Rectopexy ◽  
Delorme’S Procedure ◽  
Group 2 ◽  
Delorme's Procedure

Background: There are versatile operative techniques for treating complete rectal prolapse. Every procedure has some advantages and disadvantages. Delorme’s procedure and abdominal rectopexy (Well’s procedure) have gained more popularity. But to determine which approach is better, it is needed to evaluate the functional outcome of both procedures. Objective: To compare the outcome of Delorme’s procedure and abdominal rectopexy to treat complete rectal prolapse. Methodology: A randomized control trial was conducted in 25 patients with complete rectal prolapse in the department of Surgery, RMCH. They were divided into two groups by randomization. Fifteen patients included in Group-I underwent Delorme’s procedure, and ten patients included in group-II underwent abdominal rectopexy (Well’s procedure). The outcome of both procedures was compared postoperatively.  Results: In group-1, we have found uneventful outcomes of 10 (66.66%) patients, and hemorrhage, minor incontinence, and retention of urine were found in 2(13.3%), 1(6.66), and 4(26.66%) patients, respectively. In group-2 patients, 5(50%) patients recovered uneventfully, whereas hemorrhage, surgical site infection, retention of urine, bladder dysfunction, and constipation were found in 2(20%), 1(10%), 1(10%), 1(10%) and 2(20%) patients respectively. The mean operation time in group-I was 92.86 min and in Group 2 was 124.00 min with a p-value of 0.001. The average post-operative hospital stay after Delorme’s procedure was <4 days in 4 patients and 4-6 days in the rest 11 patients. But the hospital stay is a little lengthier in the case of abdominal rectopexy (Well’s procedure), where seven patients were discharged within 4-6 days, and three patients were discharged after the 5th day of operation. In group I, expenditure was <7000 taka in 10 (66.66%) patients, whereas in group-2 , the cost was 10000-15000 in 7(70%) patients with a p-value of 0.001. Conclusion: We can conclude that Delorme’s procedure is comparatively safer and cost-effective than Well’s procedure, considering different vital parameters. TAJ 2021; 34: No-1: 40-46

Design of Portal for Improvement Controlling Sales Channel

2014 ◽  
Vol 693 ◽  
pp. 445-450
Author(s):  
Matus Peci ◽  
Pavel Vazan ◽  
Vladimir Surka
Keyword(s):  
Performance Indicators ◽  
Web Application ◽  
Business Processes ◽  
Initial Conditions ◽  
Content Management ◽  
Appropriate Technology ◽  
Content Management System ◽  
Sales Channel ◽  
Advantages And Disadvantages ◽  
Financial Costs

This paper presents design of portal that improves controlling of sales channel at initial conditions. The customer needed to display key performance indicators on the portal and thus significantly improve the efficiency of business processes after the deployment of Microsoft Dynamics CRM 2011. The aim of this paper is to choose appropriate technology to create a portal and design possible architecture of solution. Microsoft Dynamics CRM 2011 with Web Application Microsoft SharePoint platform provide a solution for process control of business processes in company that is primarily offered like as the best solution. On the other hand, we found the possibility of open source content management system DotNetNuke, which meets customer's requirements and therefore, there is a possibility to reduce financial costs when selecting this system. Finally, we evaluated considered technologies, prepared more price variations of architecture and compared advantages and disadvantages of these variations.

scholarly journals Michigan 160: a precursor to the LMC?

1991 ◽  
Vol 148 ◽  
pp. 376-377
Author(s):  
L. Staveley-Smith
Keyword(s):  
Star Formation ◽  
Dynamical Evolution ◽  
Stellar Populations ◽  
Detailed Comparison ◽  
Elliptical Galaxies ◽  
Magellanic Clouds ◽  
Formation Processes ◽  
Stellar Formation ◽  
The Galaxy ◽  
Magellanic Stream

The tidal interaction between the Magellanic Clouds and the Galaxy is an important factor in influencing the physical and dynamical evolution of the Clouds (e.g. the Magellanic Stream) as well as the genesis and evolution of their respective stellar populations. However, how important is the influence of the Galaxy? This is a key question since we know that relatively isolated, magellanic-type galaxies do exist (e.g. NGC 3109 and NGC 4449) and have been just as efficient at star-formation as the LMC. It is possible in fact that the star formation in the clouds is primarily stochastic in nature and is relatively insensitive to the global forces which seem to have shaped stellar formation processes in massive spiral and elliptical galaxies. Unsupported by a massive bulge or halo component, cold gas disks are inherently susceptible to radial and bar-like instabilities (Efstathiou et al. 1982) which are very efficient at creating the dynamical pressures required for rapid star-formation. With this in mind, a detailed comparison of 'field' magellanic-type galaxies with the LMC and SMC is of some importance.

scholarly journals On the Dynamical Evolution of Clusters of Galaxies

1978 ◽  
Vol 79 ◽  
pp. 357-375 ◽  
Author(s):  
Jeremiah P. Ostriker
Keyword(s):  
Globular Clusters ◽  
Normal Modes ◽  
Dynamical Evolution ◽  
Second Law Of Thermodynamics ◽  
Elliptical Galaxies ◽  
Second Law ◽  
Clusters Of Galaxies ◽  
Physical Processes ◽  
Rotating Systems ◽  
Accurate Picture

The theory of the dynamics of star clusters (cf. Spitzer 1975 for a review) is by now so well developed that we have, or think we have, a moderately accurate picture of the physical processes acting in and the overall evolution of spherical systems. in contrast, flattened and/or rotating systems are apparently subject to a variety of ill-understood instabilities which ultimately are a manifestation of the second law of thermodynamics; at given total energy, a system will tend to increase the fraction of its kinetic energy in disordered rather than ordered form. But spherical systems (globular clusters, elliptical galaxies, Morgan cD clusters of galaxies) are relatively smooth and featureless; they show little substructure indicating, presumably, that they are quite stable to perturbations of their fundamental normal modes, and they are normally modeled as rather “hot”, pressure supported systems.

scholarly journals A Model for the Sequence of Elliptical Galaxies

1987 ◽  
Vol 117 ◽  
pp. 367-367
Author(s):  
Rosemary F. G. Wyse ◽  
Bernard J. T. Jones
Keyword(s):  
Dark Matter ◽  
Power Spectrum ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Initial Conditions ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Density Fluctuations ◽  
Analytic Approximation ◽  
Non Linear

We present a simple model for the formation of elliptical galaxies, based on a binary clustering hierarchy of dark matter, the chemical enrichment of the gas at each level being controlled by supernovae. The initial conditions for the non-linear phases of galaxy formation are set by the post-recombination power spectrum of density fluctuations. We investigate two models for this power spectrum - the first is a straightforward power law, |δk|2 ∝ kn, and the second is Peeble's analytic approximation to the emergent spectrum in a universe dominated by cold dark matter. The normalisation is chosen such that on some scale, say M ∼ 1012M⊙, the objects that condense out have properties - radius and velocity dispersion - resembling ‘typical’ galaxies. There is some ambiguity in this due to the poorly determined mass-to-light ratio of a typical elliptical galaxy — we look at two normalisations, σ1D ∼ 350kms−1 and σ1D ∼ 140kms−1. The choice determines which of Compton cooling or hydrogen cooling is more important during the galaxy formation period. The non-linear behaviour of the perturbations is treated by the homogeneous sphere approximation.

scholarly journals The Evolution of Galaxies in Clusters

2003 ◽  
Vol 208 ◽  
pp. 237-244 ◽  
Author(s):  
John Dubinski ◽  
Dan Koranyi ◽  
Margaret Geller
Keyword(s):  
Spiral Galaxies ◽  
Dynamical Evolution ◽  
Elliptical Galaxies ◽  
Diffuse Light ◽  
Fundamental Plane ◽  
Numerical Investigations ◽  
Evolution Of Galaxies ◽  
Density Relationship ◽  
Velocity Dispersions

We report on recent numerical investigations of the dynamical evolution of galaxies in clusters. Simulations of spiral galaxies falling into forming clusters show the development of the morphology-density relationship and the formation of regular and giant elliptical galaxies. The regular elliptical merger remnants end up in a fundamental plane very similar to the observed relation. The giant ellipticals have much in common with their real counterparts but their central velocity dispersions are too high. We also quantify the amount and distribution of diffuse light in clusters.

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