Astron. Astrophys. 319, 435-449 (1997)

Kinematics of the local universe

IV. Type dependence in the diameter Tully-Fisher relation and implications
on the mass-luminosity structure

G. Theureau ¹, M. Hanski ², P. Teerikorpi ², L. Bottinelli ^{1, 3}, T. Ekholm ², L. Gouguenheim ^{1, 3} and G. Paturel <sup>4

1</sup> Observatoire de Paris-Meudon, CNRS URA1757, F-92195 Meudon Principal Cedex, France
² Tuorla Observatory, FIN-21500 Piikkiö, Finland
³ Université Paris-Sud, F-91405 Orsay, France
⁴ Observatoire de Lyon, F-69230 Saint-Genis Laval, France

Received 8 December 1995 / Accepted 14 August 1996

Abstract

There is a type dependence in the diameter (Tully-Fisher) TF relation in the spiral galaxy range . This dependence appears as a zero-point shift from one type to another, while the slope seems to remain constant, close to 0.5 (inverse relation) as expected from our simple disc + bulge + dark halo model. The model also predicts well the amount of the shifts, when reasonable values of the mass-to-luminosity ratios of the disc and bulge components are used. A method to study the dark mass fraction in different galaxy types, based on the model, is introduced. First applications suggest that in the range the value of within the radius that the TF-measurements refer to. There are also zero-point shifts in the B -magnitude TF-relation (the inverse slope 0.1 according to our work), though smaller than in the diameter relation, as expected from the model. The found type dependencies will diminish the scatter in the TF-relations and facilitate their use in our KLUN programme for measuring the kinematics of the local galaxy universe.

Key words: galaxies: spiral galaxies: photometry galaxies: distances and redshifts galaxies: structure astronomical data bases: miscellaneous

Send offprint requests to: G. Theureau

© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998

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