Vorontsov-Velyaminov (VV) rows are straight-line segments which occur within spiral arms of grand design galaxies.  The rows are named after the first scientist who studied them 60 years ago – Dr. Boris Vorontsov-Velyaminov of Russia.  

The angle between two adjacent segments of a row is 120 degrees on average (with a standard deviation of 10 degrees).  The length of a row increases linearly with its distance from the core.

This poster includes galaxies which have VV rows that I find interesting.  I used the mouseover feature to highlight the rows which seem clear to me, but their identification is subjective, especially for non-face-on galaxies.   

These rows are fascinating me for 3 reasons:
1.  Straight lines within a rotating disk look beautiful but somehow are unsettling to me.
2.  They are not common, occurring in only about 6% of all spiral galaxies with well-developed spiral patterns.
3.  Most importantly, the reasons for their formation are not understood. 

The formation of VV rows is believed to be linked to the powerful star formation shock fronts that occur in density waves along the spiral arms.  But examining the poster carefully, it is hard to find a pattern to VV row formation.  Many galaxy disks look similar in their gas, dust and arm structure, but have VV rows on one side and not the other.  It is almost as if some unseen force is contributing to the row formation.   

A phenomenon similar to VV rows is the occurrence of a closed hexagon shape in the mid-region of the disk, which was the subject of a previous poster.  The hexagons have included angles of the same 120 degree measurement as VV rows. 

If you would like to read more about any of these objects, each of the objects in the poster has previously been uploaded and described individually on Astrobin. They all reside in my Astrobin VV Rows Collection.

If you would like to access all my DSO compilation posters, please click here.