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Barred Spirals and Formation of Spiral Arms by Galaxies
Nature, 1965SO far the formation of spiral arms, especially regular arms, has not been satisfactorily explained. The investigation of this phenomenon can be facilitated by an analysis of similar, but more peculiar, objects—barred spirals. A characteristic barred galaxy has a straight bar, which at the ends transforms abruptly into spiral arms.
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Shape and amplitude of spiral arms
Publications of the Astronomical Society of the Pacific, 1993The variation of the azimuthal shape of spiral arms is estimated through numerical models simulating a two-armed spiral perturbation in galactic disks. Significant changes as a function of perturbation amplitude and location relative to resonances are found. Models with radial force perturbations larger than 5% show significant nonlinear effects. These
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1992 Symposium on Antenna Technology and Applied Electromagnetics, 1992
An array consisting of four-by-four spiral antennas is constructed using the pair-element (PE) technique. The 3-dB axial ratio bandwidth is improved to 8.9% by the PE technique from 3.8% for an array without using the PE technique. The −14-dB return loss bandwidth is widened to 6.4% from 3.6%.
Hiroaki Mimaki +4 more
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An array consisting of four-by-four spiral antennas is constructed using the pair-element (PE) technique. The 3-dB axial ratio bandwidth is improved to 8.9% by the PE technique from 3.8% for an array without using the PE technique. The −14-dB return loss bandwidth is widened to 6.4% from 3.6%.
Hiroaki Mimaki +4 more
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Galactic Spiral Arms and Evolution [PDF]
Publications of the Astronomical Society of Australia, 1973 It is more than 120 years since the discovery of spiral galaxies, and naturally there has been much speculation on their origin. The vital clue is the composition of the arms, and it is now known that the arms are patterns of newly formed, and hence very luminous, stars.
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Publications of the Astronomical Society of the Pacific, 1990
Pulsars are used to trace the spiral arms of the Galaxy. Present pulsar characteristics are used to divide them into two pulsar types as defined by Huang (1987). The ages of Type II pulsars and the galactic rotation curve are used to determine their position at birth.
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Pulsars are used to trace the spiral arms of the Galaxy. Present pulsar characteristics are used to divide them into two pulsar types as defined by Huang (1987). The ages of Type II pulsars and the galactic rotation curve are used to determine their position at birth.
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A remark on the arms race spiral
Kybernetes, 2011PurposeThe purpose of this paper is to explain the tendency of escalation of a regular bilateral arms race, or the arms race spiral.Design/methodology/approachInspired by the Richardson‐type models, a system of two differential equations is used for describing a bilateral arms race.
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Multicolor photometry of spiral arms
Symposium - International Astronomical Union, 1966This paper describes the use of multicolor photometry to examine differences in stellar population across an arm of a spiral galaxy. We know that spiral arms are the loci of contemporary star formation, but we have no assurance that those loci are frozen in the rotating material of the galactic disk.
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2008
The controversy surrounding the delineation of molecular spiral structure in the Galaxy emphasizes that spiral structure can best be understood by observing external galaxies with high angular resolution. M51, the galaxy in which spiral structure was first discerned, is the obvious galaxy to observe. Lo et al.
Vogel, S. N. +3 more
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The controversy surrounding the delineation of molecular spiral structure in the Galaxy emphasizes that spiral structure can best be understood by observing external galaxies with high angular resolution. M51, the galaxy in which spiral structure was first discerned, is the obvious galaxy to observe. Lo et al.
Vogel, S. N. +3 more
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Spiral Arms as Ejection Phenomena
1987Magnetic fields are difficult to measure in galaxies. If we can identify accompanying phenomena perhaps we can trace the fields in a larger number of galaxies and under different conditions, thereby attempting to understand the nature and origin of magnetic fields.
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1991
Spiral galaxies are often spectacular and pretty looking objects, and as such capture the imagination of many astronomers. The problems of the occurrence, formation and maintenance of spiral structure continue to be popular, and a vast literature exists on the subject.
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Spiral galaxies are often spectacular and pretty looking objects, and as such capture the imagination of many astronomers. The problems of the occurrence, formation and maintenance of spiral structure continue to be popular, and a vast literature exists on the subject.
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