scholarly journals What is the Number of Spiral Galaxies in Compact Groups?

1990 ◽  
Vol 124 ◽  
pp. 105-114
Author(s):  
N. A. Tikhonov
Keyword(s):  
Spiral Galaxies ◽  
Compact Groups ◽  
Galaxy Morphology

AbstractThe distribution of morphological types of galaxies in compact groups is studied on plates from the 6 m telescope. In compact groups there are 57% galaxies of late morphological types (S + Irr), 23% lenticulars (SO) and 20% ellipical galaxies. The morphological content of compact groups is very nearly the same as in loose groups. There is no dependence of galaxy morphology on density in all compact groups (and possibly in loose groups). Genuine compact groups form only 60% if Hickson’s list.

scholarly journals Mass Distribution in Compact Groups

2000 ◽  
Vol 174 ◽  
pp. 377-380 ◽  
Author(s):  
J. Perea ◽  
A. del Olmo ◽  
L. Verdes-Montenegro ◽  
M. S. Yun ◽  
W.K. Huchtmeier ◽  
...  
Keyword(s):  
Compact Group ◽  
Mass Distribution ◽  
Spiral Galaxies ◽  
Main Group ◽  
Stable System ◽  
Compact Groups ◽  
Dark Halo ◽  
Potential Well ◽  
Redshift Surveys ◽  
Satellite Galaxies

AbstractNew redshift surveys of galaxies in the field of compact groups have discovered a population of faint galaxies which act as satellites orbiting in the potential well of the bright group. Here we analyze the mass distribution of the groups by comparing the mass derived from the bright members and the mass obtained from the satellite galaxies. Our analysis indicates the presence of a dark halo around the main group with a mass roughly four times that measured for the dominant galaxies of the compact group.We found that heavier halos are ruled out by the observations when comparing the distribution of positions and redshifts of the satellite galaxies with the distribution of satellites of isolated spiral galaxies. The results agree with a picture where compact groups may form a stable system with galaxies moving in a common dark halo.

scholarly journals Nonparametric galaxy morphology from UV to submm wavelengths

2020 ◽  
Vol 641 ◽  
pp. A119
Author(s):  
Maarten Baes ◽  
Angelos Nersesian ◽  
Viviana Casasola ◽  
Simone Bianchi ◽  
Letizia P. Cassarà ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Spiral Galaxies ◽  
Formation Rate ◽  
Stellar Mass ◽  
Asymmetry Index ◽  
Warning Sign ◽  
Smooth Component ◽  
Dust Mass ◽  
Multi Wavelength ◽  
Galaxy Morphology

We present the first nonparametric morphological analysis of a set of spiral galaxies from UV to submillimeter (submm) wavelengths. Our study is based on high-quality multi-wavelength imaging for nine well-resolved spiral galaxies from the DustPedia database, combined with nonparametric morphology indicators calculated in a consistent way using the StatMorph package. We measure the half-light radius, the concentration index, the asymmetry index, the smoothness index, the Gini coefficient, and the M20 indicator in various wavebands from UV to submm wavelengths, and in stellar mass, dust mass, and star formation rate maps. We find that the interstellar dust in galaxies is distributed in a more extended, less centrally concentrated, more asymmetric, and more clumpy way than the stars are. This is particularly evident when comparing morphological indicators based on the stellar mass and dust mass maps. This should serve as a warning sign against treating the dust in galaxies as a simple smooth component. We argue that the nonparametric galaxy morphology of galaxies from UV to submm wavelengths is an interesting test for cosmological hydrodynamics simulations.

Mathematical Classification of the Spiral and Ring Galaxy Morphologies Based on the Fractional Trigonometry

2015 ◽  
Author(s):  
Carl F. Lorenzo ◽  
Tom T. Hartley
Keyword(s):  
Mathematical Description ◽  
Spiral Galaxies ◽  
Optical Center ◽  
Direct Inference ◽  
High Quality ◽  
Geometric Center ◽  
The Galaxy ◽  
Ongoing Development ◽  
Galaxy Morphology

The ongoing development of the fractional trigonometry has created a new set of spiral functions, the fractional spiral functions. These spirals include both barred and normal spirals in a common formulation. This paper studies the applicability of the fractional spirals to the mathematical classification of spiral and ring galaxy morphologies. The fractional spirals are found to provide a high quality fit to a variety of ring and spiral galaxies over a significant range of the spiral length. Further, the r–s character of the de Vaucouleurs classification is found to relate to particular parameters of the spirals. Additional benefits include; direct inference of galaxies inclination, estimates of major deviations of the galaxy optical center from the geometric center, and further application of the mathematical description of the galaxy morphology.

scholarly journals Blue Ellipticals in Compact Groups

1990 ◽  
Vol 124 ◽  
pp. 99-103
Author(s):  
Stephen E. Zepf ◽  
Bradley C. Whitmore
Keyword(s):  
Compact Group ◽  
Stellar Evolution ◽  
Spiral Galaxies ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Compact Groups ◽  
Blue Color ◽  
Random Errors ◽  
Dynamical Models ◽  
Group Environment

AbstractWe examine the hypothesis that mergers of spiral galaxies make elliptical galaxies by studying galaxies in compact groups. We combine dynamical models of the merger-rich compact group environment with stellar evolution models and predict that roughly 15% of compact group ellipticals should be 0.15 mag bluer in B – R color than normal ellipticals. The published colors of these galaxies suggest the existence of this predicted blue population, but a normal distribution with large random errors can not be ruled out based on these data alone. However, we have new UBVRI data which confirm the blue color of the two ellipticals with blue B – R colors for which we have our own colors. This confirmation of a population of blue ellipticals indicates that interactions are occurring in compact groups, but a blue color in one index alone does not require that these ellipticals are recent products of the merger of two spirals. We demonstrate how optical spectroscopy in the blue may distinguish between a true spiral + spiral merger and the swallowing of a gas-rich system by an already formed elliptical. We also show that the sum of the luminosity of the galaxies in each group is consistent with the hypothesis that the final stage in the evolution of a compact group is an elliptical galaxy.

scholarly journals The Role of Environment in the Origin of Radio Emission from Galaxies

1987 ◽  
Vol 121 ◽  
pp. 411-414
Author(s):  
T.K. Menon
Keyword(s):  
Radio Emission ◽  
Compact Group ◽  
Radio Source ◽  
Spiral Galaxies ◽  
Compact Groups ◽  
Radio Radiation ◽  
Luminosity Functions ◽  
Group Galaxy ◽  
Absolute Luminosity

The influence of the environment on the origin of radio radiation from galaxies is studied by compairing the occurence of radio emission in galaxies in compact high density groups of Hickson (1982) with that in field galaxies of similar types. The study shows that the fractional luminosity functions of elliptical and spiral galaxies in compact groups are similar in shape to that of field galaxies but the probability of a compact group galaxy being a radio source is 5 to 10 times greater than that of an isolated galaxy of the same type. Radio Loud group ellipticals tend to be the optically brightest galaxy in the group independent of their absolute luminosity.

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