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Astron. Astrophys. 339, 409-422 (1998)

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5. Summary

We summarize here the main conclusions of this paper.

  1. The comparison of bulge and disk NIR average colors and mass-to-light ratios to stellar population synthesis models suggests that the bulges of our sample galaxies are younger and more metal rich than the disks.

  2. NIR M/L's appear to vary with disk luminosity, consistently with the trend in the B band, and the [FORMULA] color-luminosity relation. Such a trend can be probably imputed to a systematic variation of the disk average stellar population with luminosity, due to a variation of either star formation history or age, but not of metallicity.

  3. We find no clear evidence to prefer either standard Newtonian gravitation plus dark halos or modified gravitation, as the quality of the fits under both paradigms is comparable. The value of the critical acceleration parameter [FORMULA] that best accommodates the sample as a whole is [FORMULA] cm s-2.

  4. The dark halo parameters we obtain for six of our galaxies are roughly in agreement with the values obtained for late type spirals from B-band photometry. In particular our data are consistent with the correlation, already noted by PSS, between dark-to-visible mass ratio and luminosity.

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© European Southern Observatory (ESO) 1998

Online publication: October 21, 1998