Results 21 to 30 of about 25,712 (75)

Radial distributions of arm-gas offsets as an observational test of spiral theories [PDF]

, 2015
Theories of stellar spiral arms in disk galaxies can be grouped into two classes based on the longevity of a spiral arm. Although the quasi-stationary density wave theory supposes that spirals are rigidly-rotating, long-lived patterns, the dynamic spiral theory predicts that spirals are differentially-rotating, transient, recurrent patterns.
arxiv   +1 more source

The Myth of the Molecular Ring [PDF]

, 2012
We investigate the structure of the Milky Way by determining how features in a spatial map correspond to CO features in a velocity map. We examine structures including logarithmic spiral arms, a ring and a bar. We explore the available parameter space, including the pitch angle of the spiral arms, radius of a ring, and rotation curve.
arxiv   +1 more source

Gas velocity patterns in simulated galaxies: Observational diagnostics of spiral structure theories [PDF]

, 2016
There are two theories of stellar spiral arms in isolated disc galaxies that model stellar spiral arms with different longevities: quasi-stationary density wave theory, which characterises spirals as rigidly rotating, long-lived patterns (i.e. steady spirals), and dynamic spiral theory, which characterises spirals as differentially rotating, transient,
arxiv   +1 more source

Stellar Motion around Spiral Arms: Gaia Mock Data [PDF]

, 2015
We compare the stellar motion around a spiral arm created in two different scenarios, transient/co-rotating spiral arms and density-wave-like spiral arms. We generate Gaia mock data from snapshots of the simulations following these two scenarios using our stellar population code, SNAPDRAGONS, which takes into account dust extinction and the expected ...
arxiv   +1 more source

A multi-wavelength study of spiral structure in galaxies. I. General characteristics in the optical [PDF]

, 2020
Different spiral generation mechanisms are expected to produce different morphological and kinematic features. In this first paper in a series we carefully study the parameters of spiral structure in 155 face-on spiral galaxies, selected from the Sloan Digital Sky Survey, in the three $gri$ bands.
arxiv   +1 more source

The Role of Spiral Arms in Galaxies

The Astrophysical Journal
Abstract We test the influence of spiral arms on the star formation activity of disk galaxies by constructing and fitting multiwavelength spectral energy distributions for the two nearby spiral galaxies NGC 628 and NGC 4321, at a spatial scale of 1–1.5 kpc.
Bingqing Sun, Daniela Calzetti, Andrew J. Battisti   +2 more
openaire   +3 more sources

Massive Stars in the Nuclei and Arms of Spirals [PDF]

Proceedings of the International Astronomical Union, 2007
AbstractMany of the properties of massive stars in external galaxies, such as chemical compositions, mass functions, and ionizing fluxes, can be derived from the study of the associated clouds of ionized gas. Moreover, the signatures of Wolf-Rayet stars are often detected in the spectra of extragalactic H ii regions.
openaire   +2 more sources

Effects of Spiral Arms on Star Formation in Nuclear Rings of Barred-spiral Galaxies [PDF]

, 2014
We use hydrodynamic simulations to study the effect of spiral arms on the star formation rate (SFR) occurring in nuclear rings of barred-spiral galaxies. We find that spiral arms can be an efficient means of gas transport from the outskirts to the central parts, provided that the arms are rotating slower than the bar.
arxiv   +1 more source

Magnetic spiral arms in galaxy haloes [PDF]

Monthly Notices of the Royal Astronomical Society, 2017
We seek the conditions for a {\it steady} mean field galactic dynamo. The parameter set is reduced to those appearing in the $ ^2$ and $ / $ dynamo, namely velocity amplitudes, and the ratio of sub-scale helicity to diffusivity. The parameters can be allowed to vary on conical spirals.
openaire   +2 more sources

Spiral arm triggering of star formation [PDF]

Proceedings of the International Astronomical Union, 2006
AbstractWe present numerical simulations of the passage of clumpy gas through a galactic spiral shock, the subsequent formation of giant molecular clouds (GMCs) and the triggering of star formation. The spiral shock forms dense clouds while dissipating kinetic energy, producing regions that are locally gravitationally bound and collapse to form stars ...
Clare Dobbs, Ian A. Bonnell
openaire   +4 more sources