Results 261 to 270 of about 109,364 (298)

Pulsars as spiral arm tracers

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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Two-arm eccentric spiral antenna

IEEE Transactions on Antennas and Propagation, 1997
This paper presents a free-space analysis of a planar two-arm eccentric spiral antenna. The eccentricity generates a circularly polarized wave with the main beam directed off-normal to the spiral plane. Input impedance and radiation characteristics are calculated from the current distribution generated by a method of moments solution.
R.T. Gloutak, N.G. Alexopoulous
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Multicolor photometry of spiral arms

Symposium - International Astronomical Union, 1966
This 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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Galactic Spiral Arms and Evolution

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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Geometry of Spiral Galaxy Arms

Astrophysics and Space Science, 2003
The previous work (He, 2001) on image analysis of over one hundred nearby galaxies indicates that for any spiral galaxy image of small inclination there is evidence of two sets of iso-ratio curves in different scales which, like curvilineal coordinate lines, expand over different galaxy components.
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Molecular spiral arms in M51

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., Kulkarni, S. R., Scoville, N. Z., Hester, J.   +3 more
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Ordered and chaotic spiral arms

Astronomische Nachrichten, 2008
AbstractThe stellar flow at the arms of spiral galaxies is qualitatively different among different morphological types. The stars that reinforce the spiral arms can be either participating in an ordered or in a chaotic flow. Ordered flows are associated with normal (non‐barred) spiral galaxies.
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Spiral Arm Waves in Galaxies

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 Arms as Ejection Phenomena

1987
Magnetic 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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Barred Spirals and Formation of Spiral Arms by Galaxies

Nature, 1965
SO 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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