Bibcode
del Río, M. S.; Cepa, J.
Referencia bibliográfica
Astronomy and Astrophysics Supplement, v.134, p.333-358
Fecha de publicación:
1
1999
Número de citas
8
Número de citas referidas
7
Descripción
A Fourier analysis of the intensity distribution in the planes of nine
spiral galaxies is performed. In terms of the arm classification scheme
of cite[Elmegreen & Elmegreen (1987)]{ee87} seven of the galaxies
have well-defined arms (classes 12 and 9) and two have intermediate-type
arms (class 5). The galaxies studied are NGC 157, 753, 895, 4321, 6764,
6814, 6951, 7479 and 7723. For each object Johnson B-band images are
available which are decomposed into angular components, for different
angular periodicities. No a priori assumption is made concerning the
form of the arms. The base function used in the analysis is a
logarithmic spiral. The main result obtained with this method is that
the dominant component (or mode) usually changes at corotation. In some
cases, this change to a different mode persists only for a short range
about corotation, but in other cases the change is permanent. The
agreement between pitch angles found with this method and by fitting
logarithmic spirals to mean arm positions (del Río & Cepa
1998b, hereafter cite[Paper III]{p3}) is good, except for those cases
where bars are strong and dominant. Finally, a comparison is made with
the ``symmetrization'' method introduced by Elmegreen, Elmegreen &
Montenegro (1992, hereafter EEM), which also shows the different
symmetric components.