منابع مشابه
Secular evolution in galaxies
New observations in favour of a significant role of secular evolution are reviewed: central star formation boosted in pseudo-bulge barred galaxies, relations between bulge and disk, evidence for rejuvenated bulges. Numerical simulations have shown that secular evolution can occur through a cycle of bar formation and destruction, in which the gas plays a major role. Since bars are weakened or de...
متن کاملSecular Evolution in Barred Galaxies
A strong bar rotating within a massive halo should lose angular momentum to the halo through dynamical friction, as predicted by Weinberg. We have conducted fully self-consistent, numerical simulations of barred galaxy models with a live halo population and find that bars are indeed braked very rapidly. Specifically, we find that the bar slows sufficiently within a few rotation periods that the...
متن کاملSecular Evolution of Spiral Galaxies
It is now a well established fact that galaxies undergo significant morphological transformation during their lifetimes, manifesting as an evolution along the Hubble sequence from the late to the early Hubble types. The physical processes commonly believed to be responsible for this observed evolution trend, i.e. the major and minor mergers, as well as gas accretion under a barred potential, th...
متن کاملTime-dependent secular evolution in galaxies
Lynden-Bell & Kalnajs (1972, LBK) presented a useful formula for computing the long-range torque between spiral arms and the disk at large. The derivation uses second-order perturbation theory and assumes that the perturbation slowly grows over a very long time (the time-asymptotic limit). This formula has been widely used to predict the angular momentum transport between spiral arms and stella...
متن کاملSecular Evolution in Barred Galaxies: Observations
This paper describes a framework for studying galaxy morphology, particularly bar strength, in a quantitative manner, and presents applications of this approach that reveal observational evidence for secular evolution in bar morphology. The distribution of bar strength in galaxies is quite strongly bimodal, suggesting that barred and unbarred systems are distinct entities, and that any evolutio...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1985
ISSN: 0074-1809
DOI: 10.1017/s0074180900243258