Issue |
A&A
Volume 429, Number 3, January III 2005
|
|
---|---|---|
Page(s) | 819 - 823 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20041455 | |
Published online | 05 January 2005 |
Peculiarities and populations in elliptical galaxies*,**
II. Visual-near IR colours as population indices
Observatoire de Paris, LERMA, 77 Av. Denfert-Rochereau, 75015 Paris, France e-mail: raymond.michard@obspm.fr
Received:
11
June
2004
Accepted:
6
August
2004
As a complement to the data collected and discussed in Paper I of this series,
2MASS near-IR images have been used, in connection with available V light aperture photometry, to derive the colours ,
,
and
within the effective aperture Ae: nearly the same complete sample of 110 E-type
galaxies is treated. In Paper I these were classified, based on morphological criteria,
into the “peculiar” (or Pec) and “normal” (or Nop) subsamples.
For the Nop subsample, the derived colour indices are tightly related to
the galaxy masses, as measured by the central velocity dispersion
,
although with rather small slopes as regards
and
. For the Pec subsample, the
and
colours behave as UBV and line-indices:
part of the objects show blue residuals from the appropriate
colour-
regression, which is evidence of a younger population mixed
with the “normal” one traced by the Nop regressions; the other
shows no deviations from the Nop subsample. The distinction among Pec objects
between the YP family (NGC 2865 type), and the NP one (NGC 3923 type), is
statistically supported, and generally confirmed in specific cases.
Key words: galaxies: elliptical and lenticulars, cD / galaxies: photometry
© ESO, 2005
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