What percentage of galaxies rotate with trailing arms?
I am looking for the percentage of galaxies that rotate with trailing arms.
...
Do you know of any newer publication on this question? More recent than Pasha & Smirnov (1982) where the sample is quite small?
I think the best answer is that exact numbers are very difficult to determine.
Take for example page 5 of "Arm classifications for spiral galaxies" (1987) by D. M. Elmegreen and B. G. Elmegreen, cited over 200 times.
Affiliation: IBM Thomas J. Watson Research Center, Yorktown Heights, NY
Publication: Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 314, March 1, 1987, p. 3-9.
Page 5:
"II. THE CATALOGS
a) Selection Criteria
Table 2 includes all 708 spiral galaxies listed in the Second
Reference Catalogue of Bright Galaxies - [3rd] Edition link (A. de Vaucouleurs, G. de Vaucouleurs, and H. G. Corwin 1976), with declinations $\delta \gt -35°$, inclination-corrected radii at 25 mag arcsec$^{-2}$, R$_{25}$, greater than $1^\prime$, and inclinations less than 60°; 654 galaxies could be classified, 54 galaxies which met the criteria but were too faint, had no details (were overexposed on the POSS or were too early in Hubble type to distinguish structure) or were too inclined for reliable classification are also included in Table 2, but with designations f n, or i, respectively, instead of arm classes.
...
b) Self-Consistency Checks
Most galaxies in Table 2 were classified at least 3 times, separated by intervals of several months, as a consistency check. They were classified from both paper and glass copies of the POSS. In the de Vaucouleurs sample, ~10% of the galaxies were given different arm classes during independent examinations on the paper prints. An 8% variation occurred when the glass images were subsequently examined.
...
For the high-resolution galaxies listed in Table 3, again ~10% of the arm classes changed upon reclassification. In these cases the large amount of detail presented confusion; irregular features were given more or less weight at different times of classification. Arm classifications become increasingly difficult for very small, faint galaxies. The cutoff of $1 ^\prime$ radius for the galaxies in Table 2 represents a minimum practical size for classification from the POSS.
As you can see, even with expert examination multiple times of the same data, determination of exact numbers with any accuracy is impossible at the present time. A guess is "most of them", an exception example is: NGC 4622 (also called a backward galaxy).
