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B/T-ratios in the Hubble sequence

Published online by Cambridge University Press:  01 August 2006

Eija Laurikainen ,
H. Salo ,
R. Buta ,
J. H. Knapen ,
T. Speltincx  and
D. L. Block
Eija Laurikainen
Affiliation:
Division of Astronomy/Dept. of Phys. Sci., Univ. of Oulu, Finland email: eija.laurikainen@oulu.fi
H. Salo
Affiliation:
Division of Astronomy/Dept. of Phys. Sci., Univ. of Oulu, Finland email: eija.laurikainen@oulu.fi
R. Buta
Affiliation:
Department of Physics and Astronomy, Univ. of Alabama, USA
J. H. Knapen
Affiliation:
Centre for Astrophysics Research, Univ. of Hertfordshire, UK
T. Speltincx
Affiliation:
Division of Astronomy/Dept. of Phys. Sci., Univ. of Oulu, Finland email: eija.laurikainen@oulu.fi
D. L. Block
Affiliation:
School of Computational and Applied Mathematics, Univ. of Witwatersrand
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Abstract

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We discuss bulges in the Hubble sequence, based on the analysis of deep near-IR images for a sample of 216 nearby galaxies. Using a 2D multicomponent decomposition code, we find that the average bulge-to-total (B/T) flux ratio is less than 0.25 across all morphological types. Even 50% of the early-type galaxies (S0-S0/a) are found to have nuclear bars, inner disks or nuclear rings inside the bulge. Also, the shape parameter of the bulge is on average ≤2 for all Hubble types. Our results are consistent with the picture in which bulges even in many early-type galaxies were formed by secular evolutionary processes. We find two galaxies that might be stripped spirals, belonging to the so far empty S0c morphological class introduced by van den Bergh (1979).

Keywords

galaxies: bulgesgalaxies: evolutiongalaxies: fundamental parameters
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S235: Galaxy Evolution Across the Hubble Time , August 2006 , pp. 36 - 38
Copyright
Copyright © International Astronomical Union 2007

References

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