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A Possible Evolutionary Scenario for NGC 7217

Published online by Cambridge University Press:  25 May 2016

E. Athanassoula ,
A. Bosma ,
B. Guivarch  and
L. Verdes-Montenegro
E. Athanassoula
Affiliation:
Observatoire de Marseille, 2 Place Le Verrier, 13248 Marseille Cedex 4, FRANCE
A. Bosma
Affiliation:
Observatoire de Marseille, 2 Place Le Verrier, 13248 Marseille Cedex 4, FRANCE
B. Guivarch
Affiliation:
Observatoire de Marseille, 2 Place Le Verrier, 13248 Marseille Cedex 4, FRANCE
L. Verdes-Montenegro
Affiliation:
Instituto di Astrofisica di Andalucia, Apdo. Correos 3004, E-18080 Granada, SPAIN

Extract

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NGC 7217 is an ordinary spiral galaxy with three rings whose size ratios are such that they can be associated with resonances, as for barred spirals. From 21-cm HI line data and BVRI CCD-images of this galaxy we find (cf. Verdes-Montenegro et al. 1995) : 1) a nuclear ring strong in Hα, 2) an inner ring seen clearly in a B - I colour map, and 3) an outer ring, with blue colours and strong HI-emission. After deprojection the disk has a mean ellipticity of 0.04 ± 0.01, while the position angle of the deprojected galaxy changes suddenly at 65″ radius, where the minor axis becomes major axis. Thus a very mild oval distortion could exist, with the outer ring perpendicular to the oval. Merrifield and Kuijken (1994) find from the stellar kinematics that about 20 – 30 % of the stars are in retrograde orbits.

Type
Poster Papers
Information
Symposium - International Astronomical Union , Volume 171: New Light on Galaxy Evolution , 1996 , pp. 339
Copyright
Copyright © Kluwer 1996