Evidence for leading spiral arm formation in NGC 7479

Beckman, J.; Cepa, J.
Bibliographical reference

(Instituto de Astrofisica de Canarias and Comision Interministerial de Ciencia y Tecnologia, Summer School on Evolutionary Phenomena in Galaxies, Puerto de la Cruz, Spain, July 4-15, 1988) Astrophysics and Space Science (ISSN 0004-640X), vol. 156, no. 1-2, June 1989, p. 199-204.

Advertised on:
6
1989
Number of authors
2
IAC number of authors
0
Citations
2
Refereed citations
2
Description
Azimuthal profiles of the spiral NGC 7479 in the B and I passbands have been analyzed using a subset of the azimuthal parameters proposed by Beckman and Cepa (1989), to look for the presence of shock fronts in the arms, as predicted by the density wave theory. The sign of the skewness parameter, showing that beyond the corotation radius the concave side of the southern arm shows steeper profiles in both colors, is an indicator that the arm studied is a 'leading' structure. A color gradient in the arm, with the B intensity peak of the profile nearer to the shock front than the I peck is also measured. The measured angular shift, when converted to time drift assuming that the bar ends near the corotation radius, is consistent with the drift expected for an 'aging' stellar population.