Why Are Some Galaxies Not Barred?
نویسندگان
چکیده
منابع مشابه
Barred Galaxies
Theoretical studies suggest that large-scale stellar bars can be highly effective in delivering gas to the central few hundred parsecs of a spiral galaxy, which may then initiate rapid star formation. Further instabilities may lead to additional inflow to physical scales relevant for active galactic nuclei. We test these predictions in light of recent observations. Compared to unbarred spirals,...
متن کاملObservations of Barred Galaxies
We review general observational properties of bars in galaxies, and relations between bars, their dynamics, and (circum)nuclear activity. We consider new measurements of bar fractions and of the distribution of bars with host type, bar strength, and bar pattern speeds. Bars redistribute material radially, leading to flattened abundance gradients and a diminished degree of disk-wide two-fold sym...
متن کاملDynamics of Barred Galaxies
Some 30% of disc galaxies have a pronounced central bar feature in the disc plane and many more have weaker features of a similar kind. Kinematic data indicate that the bar constitutes a major non-axisymmetric component of the mass distribution and that the bar pattern tumbles rapidly about the axis normal to the disc plane. The observed motions are consistent with material within the bar strea...
متن کاملDouble-Barred Galaxies
I present a brief review of what is known about double-barred galaxies, where a small (“inner”) bar is nested inside a larger (“outer”) bar; the review is focused primarily on their demographics and photometric properties. Roughly 20% of S0–Sb galaxies are doublebarred; they may be rarer in later Hubble types. Inner bars are typically ∼500 pc in radius (∼12% the size of outer bars), but sizes r...
متن کاملResonances in Barred Galaxies
The inner parts of many spiral galaxies are dominated by bars. These are strong nonaxisymmetric features which significantly affect orbits of stars and dark matter particles. One of the main effects is the dynamical resonances between galactic material and the bar. We detect and characterize these resonances in N-body models of barred galaxies by measuring angular and radial frequencies of indi...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2018
ISSN: 1538-4357
DOI: 10.3847/1538-4357/aabacd