SIMBAD references

1999MNRAS.308..321C - Mon. Not. R. Astron. Soc., 308, 321-332 (1999/September-2)

Spiral patterns with straight arm segments.


Abstract (from CDS):

The phenomenon of `rows', which are straight geometrical segments in the spiral arms of galaxies, is studied. The Whirlpool nebula, Messier 51 (NGC 5194) in Canes Venatici, is considered to be an example of a giant grand design galaxy. Optical photographs, Hα, ultraviolet and far-ultraviolet images, CO, 21-cm and synchrotron emission maps, and a Ks-band mosaic of M51 are studied. With this observational material, multiple rows can be recognized in the spiral arms of the galaxy. The rows comprise a major part of the arms. The lengths of the rows increase almost linearly with distance from the centre. They intersect one another at an (average) angle ~2π/3. A possible physical explanation of the phenomenon of rows is discussed on the basis of the assumption that the formation of straight arm segments might be due to the gas-dynamical effect of stability of flat shock fronts, and the tendency of a slightly curved shock front to become flat. A quantitative flattening criterion enables an explanation of the geometrical properties of the arm patterns found in M51 and also in M101. A brief list of spirals with rows is given.

Abstract Copyright: 1999, Royal Astronomical Society

Journal keyword(s): instabilities - shock waves - galaxies: individual: M51 - galaxies: individual: M101 - galaxies: spiral - galaxies: structure

Simbad objects: 33

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