scholarly journals Secular evolutionary trends in ellipticals and bulges due to mergers

1993 ◽  
Vol 153 ◽  
pp. 399-400
Author(s):  
Tapan K. Chatterjee
Keyword(s):  
Relative Velocity ◽  
Structural Changes ◽  
Gravitational Interaction ◽  
Orbital Evolution ◽  
Interacting Galaxies ◽  
Evolutionary Trends ◽  
Dynamical Friction ◽  
Initial Separation ◽  
Impulsive Approximation

Using basically the impulsive approximation and a modification of the method used by Alladin S.M., (1965, Ap.J.,141, 768), and described in detail in Chatterjee T.K., (1990, IAU Col.,124, 519, 569) we study the evolution of binary interacting galaxies, leading ultimately to mergers. Each collision is characterised by the initial separation between the galaxies and the relative velocity therein. In each case the orbital evolution and largescale structural changes in the galaxies are studied by taking into account the change in relative velocity due to dynamical friction, leading ultimately to mergers. The evolution is considered from a time when the gravitational interaction between the progenitor pairs is physically significant (Chatterjee, 1992, Astroph. Sp.Sc., in press).

scholarly journals Building Dwarf Galaxies out of Merged Young Star Clusters

2002 ◽  
Vol 207 ◽  
pp. 730-732
Author(s):  
Michael Fellhauer
Keyword(s):  
Star Clusters ◽  
Young Star ◽  
Matter Content ◽  
Interacting Galaxies ◽  
Dynamical Friction ◽  
Dwarf Spheroidal Galaxies ◽  
Tidal Heating ◽  
Destructive Processes ◽  
Young Star Clusters ◽  
Parent Galaxy

Young star clusters in interacting galaxies are often found in groups or clusters of star clusters containing up to 100 single clusters. In our project we study the future fate of these clusters of star clusters. We find that the star clusters merge on time scales of a few dynamical crossing times of the super-cluster. The resulting merger object has similarities with observed dwarf ellipticals (dE). Furthermore, if destructive processes like tidal heating, dynamical friction or interaction with disc or bulge of the parent galaxy are taken into account our merger objects may evolve into objects resembling dwarf spheroidal galaxies (dSph), without the need of a high dark matter content.

scholarly journals The fate of magnetic fields in colliding galaxies

2010 ◽  
Vol 6 (S274) ◽  
pp. 376-380
Author(s):  
Hanna Kotarba ◽  
Harald Lesch ◽  
Klaus Dolag ◽  
Thorsten Naab
Keyword(s):  
Dark Matter ◽  
High Resolution ◽  
Magnetic Fields ◽  
Structure Formation ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Gravitational Interaction ◽  
Interacting Galaxies ◽  
Galactic Dynamics

AbstractThe evolution and amplification of large-scale magnetic fields in galaxies is investigated by means of high resolution simulations of interacting galaxies. The goal of our project is to consider in detail the role of gravitational interaction of galaxies for the fate of magnetic fields. Since the tidal interaction up to galaxy merging is a basic ingredient of cold-dark matter (CDM) structure formation models we think that our simulations will give important clues for the interplay of galactic dynamics and magnetic fields.

scholarly journals The Radio Emission of Interacting Galaxies

1982 ◽  
Vol 97 ◽  
pp. 93-94
Author(s):  
E. Hummel ◽  
J. M. van der Hulst ◽  
J. H. van Gorkom ◽  
C. G. Kotanyi
Keyword(s):  
Spiral Galaxies ◽  
Gravitational Interaction ◽  
The Other ◽  
Radio Continuum ◽  
Interacting Galaxies ◽  
Continuum Emission ◽  
Radio Sources ◽  
Complete Sample ◽  
Extended Emission ◽  
Straightforward Interpretation

Gravitational interaction is a straightforward interpretation of some of the peculiar optical morphologies shown by galaxies. There have also been attempts to study the effects of a gravitational interaction on the radio continuum emission. Statistically, the central radio sources (inner 1 kpc) in interacting spiral galaxies are about three times stronger than in isolated spirals; on the other hand, the intensity of the extended emission does not seem to be affected (Stocke, 1978; Hummel, 1981). Peculiar radio morphologies are not a general property of interacting galaxies, since in the complete sample studied by Hummel (1981) of spirals with a probability ≥0.8 of being physically related to their companion, less than 5% have a peculiar radio morphology.

scholarly journals Evolution of star–planet systems under magnetic braking and tidal interaction

2019 ◽  
Vol 621 ◽  
pp. A124 ◽  
Author(s):  
M. Benbakoura ◽  
V. Réville ◽  
A. S. Brun ◽  
C. Le Poncin-Lafitte ◽  
S. Mathis
Keyword(s):  
Ab Initio ◽  
Stellar Wind ◽  
Structural Changes ◽  
Rotation Period ◽  
Major Axis ◽  
Orbital Evolution ◽  
Open Clusters ◽  
Stellar Rotation ◽  
Semi Major Axis ◽  
Tidal Interaction

Context.With the discovery over the last two decades of a large diversity of exoplanetary systems, it is now of prime importance to characterize star–planet interactions and how such systems evolve.Aims.We address this question by studying systems formed by a solar-like star and a close-in planet. We focus on the stellar wind spinning down the star along its main-sequence phase and tidal interaction causing orbital evolution of the systems. Despite recent significant advances in these fields, all current models use parametric descriptions to study at least one of these effects. Our objective is to introduce ab initio prescriptions of the tidal and braking torques simultaneously, so as to improve our understanding of the underlying physics.Methods.We develop a one-dimensional (1D) numerical model of coplanar circular star–planet systems taking into account stellar structural changes, wind braking, and tidal interaction and implement it in a code called ESPEM. We follow the secular evolution of the stellar rotation and of the semi-major axis of the orbit, assuming a bilayer internal structure for the former. After comparing our predictions to recent observations and models, we perform tests to emphasize the contribution of ab initio prescriptions. Finally, we isolate four significant characteristics of star–planet systems: stellar mass, initial stellar rotation period, planetary mass and initial semi-major axis; and browse the parameter space to investigate the influence of each of them on the fate of the system.Results.Our secular model of stellar wind braking accurately reproduces the recent observations of stellar rotation in open clusters. Our results show that a planet can affect the rotation of its host star and that the resulting spin-up or spin-down depends on the orbital semi-major axis and on the joint influence of magnetic and tidal effects. The ab initio prescription for tidal dissipation that we used predicts fast outward migration of massive planets orbiting fast-rotating young stars. Finally, we provide the reader with a criterion based on the characteristics of the system that allows us to assess whether or not the planet will undergo orbital decay due to tidal interaction.

scholarly journals Orbital evolution of a massive black hole pair by dynamical friction

1994 ◽  
Vol 433 ◽  
pp. 733 ◽  
Author(s):  
Alberto Vecchio ◽  
Monica Colpi ◽  
Alexander G. Polnarev
Keyword(s):  
Black Hole ◽  
Orbital Evolution ◽  
Hole Pair ◽  
Dynamical Friction ◽  
Massive Black Hole

scholarly journals Fully Self-Consistent N-body Simulation of Star Cluster in the Galactic Center

2007 ◽  
Vol 3 (S246) ◽  
pp. 467-468
Author(s):  
M. Fujii ◽  
M. Iwasawa ◽  
Y. Funato ◽  
J. Makino
Keyword(s):  
Hybrid Algorithm ◽  
Galactic Center ◽  
Star Clusters ◽  
Orbital Evolution ◽  
Star Cluster ◽  
Small Scale ◽  
Dynamical Friction ◽  
Eccentric Orbit ◽  
Self Consistent

AbstractWe have developed a new tree-direct hybrid algorithm, “Bridge”. It can simulate small scale systems embedded within large-N systems fully self-consistently. Using this algorithm, we have performed full N-body simulations of star clusters near the Galactic center (GC) and compared the orbital evolutions of the star cluster with those obtained by “traditional” simulations, in which the orbital evolution of the star clusters is calculated from the dynamical friction formula. We found that the inspiral timescale of the star cluster is shorter than that obtained with traditional simulations. Moreover, we investigated the eccentricities of particles escaped from the star cluster. Eccentric orbit of the star cluster can naturally explain the high eccentricities of the observed stars.

scholarly journals Dynamical evolution of dense star clusters in galactic nuclei

2013 ◽  
Vol 9 (S303) ◽  
pp. 235-237
Author(s):  
Jaroslav Haas ◽  
Ladislav Šubr
Keyword(s):  
Power Law ◽  
Density Profile ◽  
Surface Density ◽  
Gravitational Interaction ◽  
Dynamical Evolution ◽  
Orbital Evolution ◽  
Stellar Disk ◽  
Central Mass ◽  
Symmetric Star ◽  
Sgr A

AbstractBy means of direct numerical N-body modeling, we investigate the orbital evolution of an initially thin, central mass dominated stellar disk. We include the perturbative gravitational influence of an extended spherically symmetric star cluster and the mutual gravitational interaction of the stars within the disk. Our results show that the two-body relaxation of the disk leads to significant changes of its radial density profile. In particular, the disk naturally evolves, for a variety of initial configurations, a similar broken power-law surface density profile. Hence, it appears that the single power-law surface density profile ∝R−2 suggested by various authors to describe the young stellar disk observed in the Sgr A* region does not match theoretical expectations.

scholarly journals The impact of tidal friction evolution on the orbital decay of ultra-short period planets

2021 ◽  
Author(s):  
Jaime A Alvarado-Montes ◽  
Mario Sucerquia ◽  
Carolina García-Carmona ◽  
Jorge I Zuluaga ◽  
Lee Spitler ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Stellar Wind ◽  
Structural Changes ◽  
Orbital Evolution ◽  
Convective Envelope ◽  
Tidal Friction ◽  
Orbital Decay ◽  
Tidal Theory ◽  
Short Period ◽  
The Impact

Abstract Unveiling the fate of ultra-short period (USP) planets may help us understand the qualitative agreement between tidal theory and the observed exoplanet distribution. Nevertheless, due to the time-varying interchange of spin-orbit angular momentum in star-planet systems, the expected amount of tidal friction is unknown and depends on the dissipative properties of stellar and planetary interiors. In this work, we couple structural changes in the star and the planet resulting from the energy released per tidal cycle and simulate the orbital evolution of USP planets and the spin-up produced on their host star. For the first time, we allow the strength of magnetic braking to vary within a model that includes photo-evaporation, drag caused by the stellar wind, stellar mass loss, and stellar wind enhancement due to the in-falling USP planet. We apply our model to the two exoplanets with the shortest periods known to date, NGTS-10b and WASP-19b. We predict they will undergo orbital decay in time-scales that depend on the evolution of the tidal dissipation reservoir inside the star, as well as the contribution of the stellar convective envelope to the transfer of angular momentum. Contrary to previous work, which predicted mid-transit time shifts of ∼30 − 190 s over 10 years, we found that such changes would be smaller than 10 s. We note this is sensitive to the assumptions about the dissipative properties of the system. Our results have important implications for the search for observational evidence of orbital decay in USP planets, using present and future observational campaigns.

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