Hostname: page-component-78c5997874-v9fdk Total loading time: 0 Render date: 2024-11-14T17:28:21.576Z Has data issue: false hasContentIssue false
  • English
  • Français

Triaxiality in the bulges of spirals: dynamical implications

Published online by Cambridge University Press:  07 August 2017

A.M. Varela ,
E. Simonneau  and
C. Muñoz–Tuñón
A.M. Varela
Affiliation:
1. Instituto de Astrofísica de Canarias, 38200, La Laguna, Tenerife, Spain
E. Simonneau
Affiliation:
2. Institut d'Astrophysique de Paris, 98 bis, Boul. Arago, 75014 Paris, France
C. Muñoz–Tuñón
Affiliation:
1. Instituto de Astrofísica de Canarias, 38200, La Laguna, Tenerife, Spain

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The presence of triaxial bulges has been suggested as a mechanism for sweeping out the interstellar gas into the nuclear zones of normal spiral galaxies, giving rise to star formation processes (Zaritsky and Lo, 1986). In an initial phase of the present study, we have analysed the bulge component of a sample of spiral galaxies, obtained using the 4.2m WHT at La Palma Observatory, selected from among those which exhibit moderate activity. The results obtained are: (a) There is evidence, from the misalignment between the semi–major axes of the isophotes of the bulge and disc components, to support the presence of triaxial bulges in these galaxies; (b) The high spatial resolution of the images allows us to sample the bulges, showing that the surface brightness distribution is not always represented by a family of homologous coaxial ellipses, but rather by a set of ellipses which precess around a common centre, and whose ellipticity varies (see Beckman et al., 1991; Varela, 1992). It is possible to reproduce this structure with a family of concentric triaxial ellipsoidal shells. The presence of a disc offers the advantage of enabling us to interpret the geometry of the bulge correctly, but poses the disadvantage of requiring to interpret the disc emission in order to reconstruct that associated only with the bulge, i.e. to decontaminate the bulge from the disc light. To this end we carried out a photometric analysis, which enabled us to effect a valid bulge/disc decomposition. The preliminary results yielded by the analysis of the bulge component (after decontaminating the disc) show the presence of “transparent” discs in the galaxies analysed.

Type
Contributed Papers
Information
Symposium - International Astronomical Union , Volume 153: Galactic Bulges , 1993 , pp. 435 - 436
Copyright
Copyright © Kluwer 1993 

References

Beckman, J.E.; Varela, A.M.; Muñoz–Tuñón, C.; Vílchez, J.M.; Cepa, J.: 1991, Astron. Astrophys., 245, 436.Google Scholar
Muñoz–Tuñón, C.; Varela, A.M.: 1991, Proc. Workshop Relationships between Active Galactic Nuclei and Starburst Galaxies, China (in press).Google Scholar
Simonneau, E.; Varela, A.M.; Muñoz–tuñón, C.: 1992, JQSRT (in press).Google Scholar
Stark, A.A.: 1977, Astrophys. J., 213, 368.CrossRefGoogle Scholar
Varela, A.M.: 1992, , .Google Scholar
Zaritsky, D.; Lo, K.Y.: 1986, Astrophys. J., 303, 66.CrossRefGoogle Scholar